Cell Adhesion Regulator Research Articles

Desmin Modulates Muscle Cell Adhesion and Migration.

Cellular adhesion and migration are key functions that are disrupted in numerous diseases. We report that desmin, a type-III muscle-specific intermediate filament, is a novel cell adhesion regulator. Expression of p.R406W mutant desmin, identified in patients with desmin-related myopathy, modified focal adhesion area and expression of adhesion-signaling genes in myogenic C2C12 cells. Satellite cells extracted from desmin-knock-out (DesKO) and desmin-knock-in-p.R405W (DesKI-R405W) mice were less adhesive and migrated faster than those from wild-type mice. Moreover, we observed mislocalized and aggregated vinculin, a key component of cell adhesion, in DesKO and DesKI-R405W muscles. Vinculin expression was also increased in desmin-related myopathy patient muscles. Together, our results establish a novel role for desmin in cell-matrix adhesion, an essential process for strength transmission, satellite cell migration and muscle regeneration. Our study links the patho-physiological mechanisms of desminopathies to adhesion/migration defects, and may lead to new cellular targets for novel therapeutic approaches.

Abstract 959: Proteomic and genetic interaction mapping of the Ras pathway reveals new effectors and vulnerabilities

Abstract The RAS oncogenes are mutated in one third of human cancers, but therapies against Ras-driven cancers have been unsuccessful. Ras proteins themselves are not yet druggable, and the Ras pathway contains uncharacterized redundancies, feedback mechanisms, and tributaries that have stymied the development of other targeted therapies. Multiple-agent combination therapies hold some promise, but their development requires a more thorough understanding of Ras cell biology than we currently possess. We therefore pursued creation of a physical and genetic map of the Ras pathway in non-small-cell lung cancer (NSCLC). Using H, K-, and NRas and twelve other Ras pathway proteins as baits, we conducted tandem affinity purification experiments to create a high-confidence protein-protein interaction (PPI) network. We integrated our data with public PPI, genetic susceptibility, and patient data to assemble an interpretable interaction map encompassing 360 proteins and 1000 physical interactions among them. Guided by the topology and annotations of this PPI map, we constructed a library of 1000 sgRNAs covering 120 genes. These were screened for pairwise genetic interactions (GIs) in A549 and H23 NSCLC lines using a dual sgRNA vector system to discover over 250 synthetic lethal genetic interactions. Each suggests a strategy for combination therapy. The combined GI/PPI network also produced myriad mechanistic hypotheses. Pursuing these, we made new discoveries that demonstrate the power of the approach. First, we find that KRas binds the cell adhesion regulator Radil, and that Ras regulates cell morphology by modulating the Rap signaling pathway. Second, we identify the critical guanine nucleotide exchange factor and effector by which KRas up-regulates macropinocytosis. Third, we demonstrate that that the in vivo physical interactions between Ras, Raf, and RalGEF family proteins depend crucially on the specific paralogs involved. The equivalent in vitro interactions are not selective, demonstrating that many undiscovered factors direct the strong specificity observed in vivo. Distinct genetic interaction patterns between paralogs in these same families support the non-equivalence of their members. Fourth, we detect a new synthetic lethal genetic interaction between the GTPase chaperone Rap1GDS1 and the GTPase RhoA. The strength of interaction varies among NSCLC lines, but correlates with the KRas dependence of each. This and other interactions show that several other small GTPases work in concert with Ras signaling to regulate tumor progression. Together, these discoveries show that our multiomic approach furthers two critical goals: it produces testable hypotheses that point to new Ras cell biology and reveals combination susceptibilities for the development of new therapies against Ras-driven cancers. Citation Format: Marcus R. Kelly, Kyuho Han, Kaja Kostyrko, Edwin E. Jeng, Nancie Mooney, Alejandro Sweet-Cordero, Michael Bassik, Peter K. Jackson. Proteomic and genetic interaction mapping of the Ras pathway reveals new effectors and vulnerabilities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 959.

Programmed death-ligand 1 expression is an unfavorable prognostic factor of hepatocellular carcinoma after archiving sustained virologic response for hepatitis C virus infection.

The aim of the present study was to study the pathological prognostic factor of initial hepatocellular carcinoma (HCC) after archiving sustained virologic response (SVR) for hepatitis C virus (HCV) infection. A single-center retrospective analysis was performed for patients who underwent hepatectomy between 2003 and 2017. We studied clinico-pathological findings of resected liver tissues in 35 patients with HCC after SVR treated by interferon (IFN group) and 13 patients with HCC after SVR treated by direct acting antivirals (DAA group). We also performed immunohistochemical staining using antibodies against programmed death-ligand 1 (PD-L1), cytokeratin 19, epithelial cell adhesion molecule (EpCAM) and regulator of G-protein signaling 5 (RGS5). PD-L1 positive HCC was observed in 6 cases of the IFN group and 4 cases of the DAA group. In the IFN group, in univariate analysis of recurrence free survival after surgery (RFS), the PD-L1 expression had a statistically significant impact (HR=6.01; P=0.02). In the multivariate analysis of RFS, PD-L1 expression significantly remained (HR=5.01; P=0.03). For both RFS and overall survival, Kaplan-Meier curves confirmed that patients with PD-L1 expression showed significantly worse prognosis (log-rank test P<0.01). Nuclear grade, RGS5 expression, and EpCAM expression were significantly higher in the PD-L1-positive HCC group compared with the PD-L1-negative HCC group (P<0.05). Therefore, PD-L1 expression may be an independent prognostic factor of surgically resected HCC after achieving SVR.

Protective effect of stromal Dickkopf-3 in prostate cancer: opposing roles for TGFBI and ECM-1

Aberrant transforming growth factor–β (TGF-β) signaling is a hallmark of the stromal microenvironment in cancer. Dickkopf-3 (Dkk-3), shown to inhibit TGF-β signaling, is downregulated in prostate cancer and upregulated in the stroma in benign prostatic hyperplasia, but the function of stromal Dkk-3 is unclear. Here we show that DKK3 silencing in WPMY-1 prostate stromal cells increases TGF-β signaling activity and that stromal cell-conditioned media inhibit prostate cancer cell invasion in a Dkk-3-dependent manner. DKK3 silencing increased the level of the cell-adhesion regulator TGF-β–induced protein (TGFBI) in stromal and epithelial cell-conditioned media, and recombinant TGFBI increased prostate cancer cell invasion. Reduced expression of Dkk-3 in patient tumors was associated with increased expression of TGFBI. DKK3 silencing reduced the level of extracellular matrix protein-1 (ECM-1) in prostate stromal cell-conditioned media but increased it in epithelial cell-conditioned media, and recombinant ECM-1 inhibited TGFBI-induced prostate cancer cell invasion. Increased ECM1 and DKK3 mRNA expression in prostate tumors was associated with increased relapse-free survival. These observations are consistent with a model in which the loss of Dkk-3 in prostate cancer leads to increased secretion of TGFBI and ECM-1, which have tumor-promoting and tumor-protective roles, respectively. Determining how the balance between the opposing roles of extracellular factors influences prostate carcinogenesis will be key to developing therapies that target the tumor microenvironment.

SIPA1 Gene Polymorphisms and the Risk of Breast Carcinoma among the Egyptian Females: A Pilot Study

Background: Multiple genes are known to influence the cancer metastasis but the effect of the germline heritable genetic polymorphisms on the predisposition and metastasis is not yet well known. Signal-induced proliferation associated gene1 (SIPA1) was considered as a modifying factor in the breast carcinoma (BC) metastasis process. Molecular studies on Sipa 1 gene suggested its essential role as cell adhesion regulator and metastasis modulator. The present study relied on the hypothesis that Sipa1 gene may be contributed to the risk of breast cancer occurrence and aggressiveness as well.Objective: We aimed to examine the association of SIPA1 single nucleotide polymorphisms (SNPs) and human breast cancer incidence and prognosis in Egyptian female patients.Patient and Methods: Two common SNPs (rs3741378 C>T and rs746429 A>G) were genotyped in 80 Egyptian females; 50 patients with breast cancer and 30 breast carcinoma free females.Results: The rs3741378 TT genotype enhanced the incidence of breast carcinoma in comparison with the genotypes rs3741378 CC and TC (X2=7.08, P=0.029), Sipa 1 rs3741378 T allele had a high frequency in BC cases compared to controls (OR (95%)=2.593 (1.339-5.02), P=0.04). Sipa 1 rs3741378 TT genotype also displayed significant association with clinical stages, grades and lymph node metastasis (X2=12.73, P=0.013), (X2=10.88, P=0.028), (X2=6.534, P=0.010; OR (95%)=0.324 [0.134-0.781]), respectively. Pointing to those patients carrying the rs3741378 TT genotype had a higher tumor progression rate with advanced tumor grades. Oppositely, these associations could not be detected for rs746429 A>G.Conclusion: Our results suggest that the Sipa1 promoter rs3741378 C>T SNP was contributed to BC risk and progression, which may be considered as a foretelling biomarker of BC risk and progression.

Relevance of iPSC-derived human PGC-like cells at the surface of embryoid bodies to prechemotaxis migrating PGCs

Pluripotent stem cell-derived human primordial germ cell-like cells (hPGCLCs) provide important opportunities to study primordial germ cells (PGCs). We robustly produced CD38+ hPGCLCs [∼43% of FACS-sorted embryoid body (EB) cells] from primed-state induced pluripotent stem cells (iPSCs) after a 72-hour transient incubation in the four chemical inhibitors (4i)-naïve reprogramming medium and showed transcriptional consistency of our hPGCLCs with hPGCLCs generated in previous studies using various and distinct protocols. Both CD38+ hPGCLCs and CD38- EB cells significantly expressed PRDM1 and TFAP2C, although PRDM1 mRNA in CD38- cells lacked the 3'-UTR harboring miRNA binding sites regulating mRNA stability. Genes up-regulated in hPGCLCs were enriched for cell migration genes, and their promoters were enriched for the binding motifs of TFAP2 (which was identified in promoters of T, NANOS3, and SOX17) and the RREB-1 cell adhesion regulator. In EBs, hPGCLCs were identified exclusively in the outermost surface monolayer as dispersed cells or cell aggregates with strong and specific expression of POU5F1/OCT4 protein. Time-lapse live cell imaging revealed active migration of hPGCLCs on Matrigel. Whereas all hPGCLCs strongly expressed the CXCR4 chemotaxis receptor, its ligand CXCL12/SDF1 was not significantly expressed in the whole EBs. Exposure of hPGCLCs to CXCL12/SDF1 induced cell migration genes and antiapoptosis genes. Thus, our study shows that transcriptionally consistent hPGCLCs can be readily produced from hiPSCs after transition of their pluripotency from the primed state using various methods and that hPGCLCs resemble the early-stage PGCs randomly migrating in the midline region of human embryos before initiation of the CXCL12/SDF1-guided chemotaxis.

Abstract 1355: Linking AP/MS-derived protein-protein interaction networks and pairwise sgRNA screens defines new KRAS effectors in non-small cell lung cancer

Abstract The KRAS oncogene is mutated in over one fourth of human cancers. Despite decades of work studying known effector pathways, no drugs in clinical use specifically target KRAS-mutant tumors. Uncharacterized feedback mechanisms and parallel pathways have stymied the treatment of KRAS-mutant tumors in patients, and the KRas protein does not easily accommodate the binding of inhibitory small molecules. These challenges demand better characterization of the physical and genetic relationships between Ras regulators and effectors. To that end, we used tandem affinity purification of Kras, Hras and Nras and twelve proteins with known regulatory or effector roles to generate a high-confidence protein-protein interaction (PPI). Interactions were cross-referenced with public PPI, genetic susceptibility, and patient data to assemble a physical PPI map annotated with important functional determinants. The final map contains 287 genes and 990 physical interactions among them. This map was used to construct a library of &amp;gt;1000 sgRNAs covering &amp;gt;100 genes of probable relevance to the Ras pathway. This library was screened for pairwise genetic effects in a dual sgRNA vector system to identify quantitative changes in the growth of the A549 NSCLC line. We will present the quantitative results of this screen and additional validation studies on several previously undescribed regulators and effectors of the Ras proteins. In particular, we highlight unknown interactions between KRAS and the cell adhesion regulator RADIL, and the specificity of Ras-family protein interaction with the Raf and Ral GEF family proteins. These data underscore the limitations of our current understanding of Kras-driven cancers and reveal their genetic vulnerabilities. Citation Format: Marcus R. Kelly. Linking AP/MS-derived protein-protein interaction networks and pairwise sgRNA screens defines new KRAS effectors in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1355. doi:10.1158/1538-7445.AM2017-1355

Cdon promotes neural crest migration by regulating N-cadherin localization

Neural crest cells (NCCs) are essential embryonic progenitor cells that are unique to vertebrates and form a remarkably complex and coordinated system of highly motile cells. Migration of NCCs occurs along specific pathways within the embryo in response to both environmental cues and cell–cell interactions within the neural crest population. Here, we demonstrate a novel role for the putative Sonic hedgehog (Shh) receptor and cell adhesion regulator, cdon, in zebrafish neural crest migration. cdon is expressed in developing premigratory NCCs but is downregulated once the cells become migratory. Knockdown of cdon results in aberrant migration of trunk NCCs: crestin positive cells can emigrate out of the neural tube but stall shortly after the initiation of migration. Live cell imaging analysis demonstrates reduced directedness of migration, increased velocity and mispositioned cell protrusions. In addition, transplantation analysis suggests that cdon is required cell-autonomously for directed NCC migration in the trunk. Interestingly, N-cadherin is mislocalized following cdon knockdown suggesting that the role of cdon in NCCs is to regulate N-cadherin localization. Our results reveal a novel role for cdon in zebrafish neural crest migration, and suggest a mechanism by which Cdon is required to localize N-cadherin to the cell membrane in migratory NCCs for directed migration.

Kaiso regulates Znf131-mediated transcriptional activation

Kaiso is a dual-specificity POZ-ZF transcription factor that regulates gene expression by binding to sequence-specific Kaiso binding sites (KBS) or methyl-CpG dinucleotide pairs. Kaiso was first identified as a binding partner for the epithelial cell adhesion regulator p120 ctn. The p120 ctn/Kaiso interaction is reminiscent of the β-catenin/TCF interaction and several studies have suggested that Kaiso is a negative regulator of the Wnt/β-catenin TCF signaling pathway. To gain further insight into Kaiso's function, we performed a yeast two-hybrid screen using the Kaiso POZ domain as bait. This screen identified the POZ-ZF protein, Znf131, as a Kaiso-specific binding partner. GST pull-down assays confirmed that the interaction is mediated via the POZ domain of each protein, and co-immunoprecipitation experiments further supported an in vivo Kaiso-Znf131 interaction. Using a C yclic A mplification and S election of T argets (CAST) approach, we identified the 12-base pair DNA palindrome sequence GTCGCR-(X) n-YGCGAC as a potential Z nf131 b inding e lement (ZBE). In vitro studies using e lectrophoretic m obility s hift a ssay (EMSA) demonstrated that Znf131 binds the ZBE via its zinc finger domain. Znf131 DNA-binding specificity was confirmed using competition assays and ZBE mutational analyses. An artificial promoter–reporter construct containing four tandem copies of the ZBE was constructed and used to assess Znf131 transcriptional properties. We observed dose-dependent transcriptional activation of this artificial promoter–reporter by Znf131 in both epithelial and fibroblast cells, suggesting that Znf131 is a transcriptional activator. Kaiso overexpression significantly decreased the Znf131-mediated transcriptional activation, and interestingly, co-expression of the Kaiso-specific interaction partner p120 ctn relieved Kaiso's inhibition of Znf131-mediated transcriptional activation. These findings indicate that Znf131 is a transcriptional activator, a less common function of POZ-ZF proteins, that is negatively regulated by its heterodimerization partner Kaiso.

Roles of mammalian Fringe in the developing cerebral cortex

Neural crest cells (NCCs) are essential embryonic progenitor cells that are unique to vertebrates and form a remarkably complex and coordinated system of highly motile cells. Migration of NCCs occurs along specific pathways within the embryo in response to both environmental cues and cell–cell interactions within the neural crest population. Here, we demonstrate a novel role for the putative Sonic hedgehog (Shh) receptor and cell adhesion regulator, cdon, in zebrafish neural crest migration. cdon is expressed in developing premigratory NCCs but is downregulated once the cells become migratory. Knockdown of cdon results in aberrant migration of trunk NCCs: crestin positive cells can emigrate out of the neural tube but stall shortly after the initiation of migration. Live cell imaging analysis demonstrates reduced directedness of migration, increased velocity and mispositioned cell protrusions. In addition, transplantation analysis suggests that cdon is required cell-autonomously for directed NCC migration in the trunk. Interestingly, N-cadherin is mislocalized following cdon knockdown suggesting that the role of cdon in NCCs is to regulate N-cadherin localization. Our results reveal a novel role for cdon in zebrafish neural crest migration, and suggest a mechanism by which Cdon is required to localize N-cadherin to the cell membrane in migratory NCCs for directed migration.

Gene expression in rats with Barrett's esophagus and esophageal adenocarcinoma induced by gastroduodenoesophageal reflux.

To study the different gene expression profiles in rats with Barrett's esophagus (BE) and esophageal adenocarcinoma (EA) induced by gastro-duodeno-esophageal reflux. Esophagoduodenostomy was performed in 8-wk old Sprague-Dawley rats to induce gastro-duodeno-esophageal reflux, and a group of rats that received sham operation served as control. Esophageal epithelial pathological tissues were dissected and frozen in liquid nitrogen immediately. The expression profiles of 4096 genes in EA and BE tissues were compared to normal esophagus epithelium in normal control (NC) by cDNA microarray. Four hundred and forty-eight genes in BE were more than three times different from those in NC, including 312 upregulated and 136 downregulated genes. Three hundred and seventy-seven genes in EA were more than three times different from those in NC, including 255 upregulated and 142 downregulated genes. Compared to BE, there were 122 upregulated and 156 downregulated genes in EA. In the present study, the interested genes were those involved in carcinogenesis. Among them, the upregulated genes included cathepsin C, aminopeptidase M, arachidonic acid epoxygenase, tryptophan-2,3-dioxygenase, ubiquitin-conjugating enzyme, cyclic GMP-stimulated phosphodiesterase, tissue inhibitor of metalloproteinase-1, betaine-homocysteine methyltransferase, lysozyme, complement 4b binding protein, complement 9 protein, insulin-like growth factor binding protein, UDP-glucuronosyltransferase, tissue inhibitor of metalloproteinase-3, aldolase B, retinoid X receptor gamma, carboxylesterase and testicular cell adhesion molecule 1. The downregulated genes included glutathione synthetase, lecithin-cholesterol acyltransferase, p55CDC, heart fatty acid binding protein, cell adhesion regulator and endothelial cell selectin ligand. Esophageal epithelium exposed excessively to harmful ingredients of duodenal and gastric reflux may develop into BE and even EA gradually. The gene expression level is different between EA and BE, and may be related to the occurrence and progression of EA.

Inhibition of melanoma cell binding to type IV collagen by analogs of cell adhesion regulator.

Integrin-mediated tumor cell adhesion to type IV collagen is believed to play a role in the invasion of basement membrane proteins and the subsequent metastatic process. The cellular protein CAR (cell adhesion regulator) has been proposed to influence integrin-mediated binding to extracellular matrix proteins, including basement membrane (type IV) collagen. Three analogs of the CAR138-142 have been tested for activity. The first contains the 138-142 sequence (CAR138-142, Val-Glu-Ile-Leu-Tyr-NH2), the second contains the 138-142 sequence with a phosphorylated Tyr [pCAR138-142, Val-Glu-Ile-Leu-Tyr(PO3H2)-NH2], and the third contains the reversed 138-142 sequence (rCAR138-142, Tyr-Leu-Ile-Glu-Val-NH2). When added extracellularly, none of the analogs had a significant affect on cell adhesion to type IV collagen. Using a novel reversible cell permeabilization method, we found that intracellular incorporation of both CAR138-142 and pCAR138-142 resulted in inhibition of cell adhesion in a dose-dependent fashion. The IC50 values were approximately 90 and approximately 10 microM for CAR138-142 and pCAR138-142, respectively. Intracellular incorporation of the rCAR138-142 peptide had no affect on cell adhesion. Fluorescence microscopy of a fluorescein-labeled CAR138-142 peptide revealed that the reversible permeabilization procedure resulted in the peptides crossing the cell membrane. Affinity chromatography of melanoma cell lysates with pCAR138-142 or rCAR138-142 attached to a solid support of magnetic beads suggested that one protein was bound uniquely by pCAR138-142. Immunoprecipitation analysis identified vinculin, a protein associated with the actin cytoskeleton, as the protein specifically bound by pCAR138-142. Immunoprecipitation with pp125FAK- or beta 1-integrin-derived mAbs gave negative results. Our study suggests that a possible therapeutic approach for inhibition of melanoma cell adhesion adhesion to extracellular matrix proteins is the use of CAR peptide analogs intracellularly.

Association of reduced cell adhesion regulator messenger RNA expression with tumor progression in human hepatocellular carcinoma.

The recently identified cell adhesion regulator (CAR) modulates the process of integrin-mediated cell adhesion. The CAR gene is located on 16q, a locus at which high levels of allelic losses have been demonstrated in advanced human hepatocellular carcinoma (HCC). We studied the possible involvement of the CAR gene in the progression of HCC. With this aim, we determined the expression of CAR mRNA in 30 cases of HCC. Matching pair samples of tumor and adjacent nontumoral liver were analyzed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The results were compared with the clinicopathological features of the patients. Every nontumoral liver tissue sample analyzed, expressed CAR mRNA. All tumor samples showed amounts of expression that were equal or lower, compared with those found in their matching controls. Thus, in 16 out of 30 cases (53.3%), CAR mRNA expression in tumor was diminished to less than one tenth of that observed in nontumoral tissue. This group of patients exhibited higher amounts of alpha-fetoprotein, and comprised tumors with poor histological differentiation (Edmondson-Steinert's grades III-IV), higher rates of intrahepatic metastasis and recurrence within the first postoperative year (p < 0.05, respectively). Tumors exhibiting low levels of CAR mRNA were also found to be diagnosed at more advanced TNM stages (p < 0.01). We conclude that downregulation of CAR mRNA expression may play an essential role in the progression of HCC.

Association of reduced cell adhesion regulator messenger RNA expression with tumor progression in human hepatocellular carcinoma

Association of reduced cell adhesion regulator messenger RNA expression with tumor progression in human hepatocellular carcinoma

Cotranscription of two RNA coding for the cell adhesion regulator and its variant in Reh leukemia cells

Human genomic DNA analysis reveals the existence of polymorphisms at the cell molecular adhesion regulator (CMAR) locus. In order to choose between the two possible open frames deduced from the variant sequence, we have sequenced both the human 5′ non-coding region and the mouse CMAR variant DNA. We found that both mRNA species coexist in human cells.

The Cell Adhesion Regulator (CAR) Gene, TaqI and Insertion/Deletion Polymorphisms, and Regional Assignment to the Peritelomeric Region of 16q by Linkage Analysis

We have identified two types of polymorphism at the CAR (cell adhesion regulator) locus. One is a conventional TaqI polymorphism and the other is an insertion/deletion polymorphism in the coding region. One has the nucleotide sequence AGTGAGGCA (Ser-Gln-Ala) at nt 271-279, whereas the variant has ACAC̄ -AGTGAGGCCC̄A(Thr-Gln-Ser-Gly-Pro). Although it is not clear whether this variation of amino acids affects the biological function of the gene product, this variant was detected in nine chromosomes among 30 unrelated Japanese individuals. Genetic linkage analysis based on the genotypes of TaqI polymorphism in CEPH families revealed close linkage of CAR to D16S7 and D16S154, which are located in the peritelomeric region of the long arm of chromosome 16.

Cloning and characterization of a gene that regulates cell adhesion.

Molecules of the cadherin and integrin families involved in cell-cell and cell-matrix adhesion have been implicated in epithelial differentiation, carcinogenesis and metastasis. Having observed that a colon cancer cell line bound avidly to collagen type I, inducing integrin-triggered glandular differentiation, we investigated the regulation of integrin function in these cells. We modified a mammalian expression cloning system that used monoclonal antibody selection to clone cell surface molecules. Using attachment to collagen type I to select for adhesive phenotype, we isolated a complementary DNA clone that increases cell adhesion to components of the extracellular matrix. The corresponding gene (cell adhesion regulator, CAR) is located on the long arm of chromosome 16 (16q) and encodes a protein of 142 amino acids, which has an N-terminal myristoylation motif and a consensus tyrosine-kinase phosphorylation site at the C terminus. Removal of this tyrosine residue abolishes enhancement of cell-matrix adhesion. This gene may encode an adhesion signal transduction molecule that functions in the suppression of tumour invasion.