Human fetuin-A Research Articles

The Evolving Role of Fetuin-A in Nonalcoholic Fatty Liver Disease: An Overview from Liver to the Heart.

Nonalcoholic fatty liver disease (NAFLD) is strongly associated to the features of metabolic syndrome which can progress to cirrhosis, liver failure and hepatocellular carcinoma. However, the most common cause of mortality in people with NAFLD is not liver-related but stems from atherosclerotic cardiovascular disease (CVD). The prevalence of NAFLD is on the rise, mainly as a consequence of its close association with two major worldwide epidemics, obesity and type 2 diabetes (T2D). The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression and CVD have not been completely elucidated. Human fetuin-A (alpha-2-Heremans Schmid glycoprotein), a glycoprotein produced by the liver and abundantly secreted into the circulation appears to play a role in insulin resistance, metabolic syndrome and inflammation. This review discusses the links between NAFLD and CVD by specifically focusing on fetuin-A’s function in the pathogenesis of NAFLD and atherosclerotic CVD.

Прогнозирование тяжести остеопороза у пациентов с ревматоидным артритом путем определения уровня фетуина-А

Aim of study. To investigate the level of dependence of osteoporosis (OP) progression severity on the level of fetuin-A (FA) in order to predict the OP progression severity in RA patients. Material and methods. We have examined a total of 110 RA patients (mean age 54.2+11.97). Th e diagnosis was established based on ACR/EULAR criteria 2010. A total of 30 conventionally healthy subjects were enrolled serving as a control group. Evaluation of bone mineral density (BMD) was performed using DXA (Lunar DPX-NT GE densitometer). The FA level was determined through indirect enzyme-linked immunoassay (Human Fetuin-A ELISA test-system). Results. Mean serum FA in healthy subjects amounted to 653.55-972.19μg/ml. We formed 2 groups of RA patients: with blood serum FA levels <653.55μg/ml (23 patients) and with normal FA values: 653.55μg/ml or higher (87 patients). A lowered FA level was revealed in 20 (86.96 %) subjects in the group of OP patients and only in 3 (13.04 %) patients with RA without OP (р<0.001). Osteoporotic bone fractures were diagnosed in 12 (13.79 %) patients in the group with normal FA levels and were absent in 75 (86.21 %) patients (р<0.001). Apart from that, RA patients with lowered FA had reliably lower mean BMD in the area of femoral neck and vertebral column as well as lower BMD total value (р<0.001). In order to determine the diagnostic accuracy of laboratory tests, the characteristic curve (ROC curve) was applied. Th e area under the ROC-curve was 0.663 with the cut-off point matching the FA level of 660.3μg/ml. Th is value corresponds with 84.72 % specifi city and 47.37 % sensitivity. Conclusion. We have revealed reliable correlations between the serum FA level in RA patients, the frequency of OP development, osteoporotic bone fractures and BMD values (p<0.001). Laboratory evaluation of FA for OP progression severity prediction for RA patients has good quality with the specifi city of 84.72 % and the sensitivity of 47.37 %.

An integrated in silico approach to understand protein–protein interactions: human meprin-β with fetuin-A

Human meprin-β, a zinc metalloprotease belonging to the astacin family, have been found to be associated with many pathological conditions like inflammatory bowel disease, fibrosis and neurodegenerative disease. The inhibition of meprin-β by various inhibitors, both macromolecular and small molecules, is crucial in the control of several diseases. Human fetuin-A, a negative acute phase protein involved in inflammatory disease, has recently been identified as an endogenous inhibitor for meprin-β. In this computational study, an integrated in silico approach was performed using existing structural information of meprin-β coupled with ab initio modelling of human fetuin-A to predict a rational model of the complex through protein–protein docking. Further, the models were optimized and validated to generate an ensemble of conformations through extensive molecular dynamics simulation. Virtual alanine scanning mutagenesis was explored to identify hotspot residues on both proteins significant for protein–protein interaction (PPI). The results of the study provide structural insight into PPI between meprin-β and fetuin-A which can be useful in designing molecules to modulate meprin-β activity. Communicated by Ramaswamy H. Sarma

Serum fetuin-A, tumor necrosis factor alpha and C-reactive protein concentrations in patients with hereditary angioedema with C1-inhibitor deficiency

Background and aimsHereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) is characterized by localized, non-pitting, and transient swelling of submucosal or subcutaneous region. Human fetuin-A is a multifunctional glycoprotein that belongs to the proteinase inhibitor cystatin superfamily and has structural similarities to the high molecular weight kininogen. Fetuin-A is also known a negative acute phase reactant with anti-inflammatory characteristics. In this study we aimed to determine serum fetuin-A, C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα) concentrations in patients with C1-INH-HAE during symptom-free period and during attacks and compare them to those of healthy controls. Further we analyzed possible relationship among these parameters as well as D-dimer levels which was known as marker of HAE attacks.Patients and methodsSerum samples of 25 C1-INH-HAE patients (8 men, 17 women, age: 33.1 ± 6.9 years, mean ± SD) were compared to 25 healthy controls (15 men, 10 women, age: 32.5 ± 7.8 years). Serum fetuin-A and TNFα concentrations were determined by ELISA, CRP and D-dimer by turbidimetry.ResultsCompared to healthy controls patients with C1-INH-HAE in the symptom-free period had significantly decreased serum fetuin-A 258 μg/ml (224–285) vs. 293 μg/ml (263–329), (median (25–75% percentiles, p = 0.035) and TNFα 2.53 ng/ml (1.70–2.83) vs. 3.47 ng/ml (2.92–4.18, p = 0.0008) concentrations. During HAE attacks fetuin-A levels increased from 258 (224–285) μg/ml to 287 (261–317) μg/ml (p = 0.021). TNFα and CRP levels did not change significantly. We found no significant correlation among fetuin-A CRP, TNFα and D-dimer levels in any of these three groups.ConclusionsPatients with C1-INH-HAE have decreased serum fetuin-A concentrations during the symptom-free period. Given the anti-inflammatory properties of fetuin-A, the increase of its levels may contribute to the counter-regulation of edema formation during C1-INH-HAE attacks.

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases

Vertebrate fetuins are multi-domain plasma-proteins of the cystatin-superfamily. Human fetuin-A is also known as AHSG, α2-Heremans-Schmid-glycoprotein. Gene-knockout in mice identified fetuin-A as essential for calcified-matrix-metabolism and bone-mineralization. Fetuin-B deficient mice, on the other hand, are female infertile due to zona pellucida ‘hardening’ caused by the metalloproteinase ovastacin in unfertilized oocytes. In wildtype mice fetuin-B inhibits the activity of ovastacin thus maintaining oocytes fertilizable. Here we asked, if fetuins affect further proteases as might be expected from their evolutionary relation to single-domain-cystatins, known as proteinase-inhibitors. We show that fetuin-A is not an inhibitor of any tested protease. In stark contrast, the closely related fetuin-B selectively inhibits astacin-metalloproteinases such as meprins and ovastacin, but not astacins of the tolloid-subfamily, nor any other proteinase. The analysis of fetuin-B expressed in various mammalian cell types, insect cells, and truncated fish-fetuin expressed in bacteria, showed that the cystatin-like domains alone are necessary and sufficient for inhibition. This report highlights fetuin-B as a specific antagonist of ovastacin and meprin-metalloproteinases. Control of ovastacin was shown to be indispensable for female fertility. Meprin inhibition, on the other hand, renders fetuin-B a potential key-player in proteolytic networks controlling angiogenesis, immune-defense, extracellular-matrix-assembly and general cell-signaling, with implications for inflammation, fibrosis, neurodegenerative disorders and cancer.

Magnetic multiwalled carbon nanotubes as nanocarrier tags for sensitive determination of fetuin in saliva

This paper reports the development and performance of an electrochemical immunosensor using magnetic multiwalled carbon nanotubes (m-MWCNTs) as nanocarrier tags for the determination of human fetuin A (HFA), a relevant biomarker of obesity, insulin resistance, and type-2 diabetes as well as for pancreatic and liver cancers and inflammatory processes. Screen-printed carbon electrodes were grafted with p-aminobezoic acid and streptavidin was covalently immobilized on the electrode surface. A biotinylated capture antibody was immobilized through streptavidin-biotin interaction and a sandwich assay configuration was implemented using m-MWCNTs conjugated with HRP and anti-HFA antibodies as the detection label. The determination of HFA was accomplished by measuring the current produced by the electrochemical reduction of benzoquinone at −200 mV upon addition of H2O2 as HRP substrate. The prepared m-MWCNTs were characterized by SEM, TEM, XRD and EDS. All the steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy and cyclic voltammetry. A linear calibration plot for HFA was found between 20 and 2000 pg/mL with a LOD value of 16 pg/mL. This performance is notably better than that reported for an ELISA kit and a chronoimpedimetric immunosensor. The favorable contribution of m-MWCNTs in comparison with MWCNTs without incorporated magnetic particles to this excellent analytical performance is also highlighted. The immunosensor selectivity against other proteins and potentially interfering compounds was excellent. In addition, the usefulness of the immunosensor was demonstrated by the analysis of HFA in saliva with minimal sample treatment.

Human Fetuin-A Rs4918 Polymorphism and its Association with Obesity in Healthy Persons and in Patients with Myocardial Infarction in Two Hungarian Cohorts.

BackgroundHuman fetuin A (AHSG) has been associated with the development of obesity, insulin resistance, type 2 diabetes mellitus, and atherosclerosis. Observations on the role of AHSG rs4918 single-nucleotide polymorphism are contradictory. We investigated the association between variants of rs4918 and parameters of obesity, lipid status, tumor necrosis factor-α (TNFα), adipokines (adiponectin, resistin, leptin), and insulin resistance in healthy persons and in patients with previous myocardial infarction.Material/MethodsThis was a cross-sectional study comprising cohort 1 (81 healthy individuals) and cohort 2 (157 patients with previous myocardial infarction). We used the allele-specific KASP genotyping assay to detect rs4918 polymorphism.ResultsIn cohort 1, G-nucleotide carriers had significantly lower serum TNFα, adiponectin, and higher leptin concentrations than in non-G carriers. These differences, however, were not observed in cohort 2. In cohort 2, G-carriers had lower BMI and waist circumferences than in non-G carriers. The G allele was more frequent among lean than obese patients (RR=1.067, 95%CI=1.053–2.651, p=0.015). An association between BMI and rs4918 polymorphism was observed among patients without diabetes (CC/CG/GG genotypes: p=0.003, G vs. non-G allele: p=0.008) but not in diabetics. In addition, a strong linearity between BMI and the CC/CG/GG genotypes (association value: 4.416, p=0.036) and the frequency of the G allele (7.420, p=0.006) could be identified. In cohort 2, non-obese, non-diabetic G-carriers still had lower BMI and waist circumferences than in non-G carriers.ConclusionsThe rs4918 minor variant is associated with lower TNFα and adiponectin, higher leptin levels in healthy persons, and more favorable anthropomorphic parameters of obesity in cohort 2.

Fetuin-A dynamics in transition cows' plasma

Around parturition and during early lactation, cows enter a state of negative energy balance (NEB) driven by the onset of lactation and a reduced dry matter intake. The major metabolic adaptation to NEB is adipose tissue lipolysis that releases nonesterified fatty acids (NEFA) into systemic circulation. High plasma NEFA predisposes cows to metabolic and inflammatory based diseases that negatively impact animal welfare and increase economic losses to dairy producers. However, not all cows with increased plasma NEFA concentrations develop a disease, thus underscoring the need for novel lipid mobilization-related biomarkers that could improve accuracy of disease prediction. In humans, high fetuin-A concentrations have been identified as an independent marker of insulin resistance and a predictor of type 2 diabetes and non-alcoholic fatty liver. Furthermore, elevated human fetuin-A concentrations are strongly associated with dyslipidemias. Fetuin-A is an abundant carrier of NEFA in plasma and is mainly expressed in hepatocytes, monocytes/macrophages, and adipocytes. Fetuin-A inhibits insulin receptor signaling and therefore increases lipolysis and NEFA efflux from adipose tissues. Despite its strong link with lipolytic processes, fetuin-A expression in plasma and its relationship with metabolic markers in transition cows remains poorly understood. The objective of this study was to evaluate the dynamics of serum fetuin-A and its association with NEFA during the transition period.

A rapid sandwich immunoassay for human fetuin A using agarose-3-aminopropyltriethoxysilane modified microtiter plate

A rapid sandwich immunoassay (IA) with enhanced signal response for human fetuin A (HFA) was developed by modifying the surface of a KOH-treated polystyrene microtiter plate (MTP) with agarose and 3-aminopropyltriethoxysilane (APTES). The agarose-APTES complex binds covalently to the hydroxyl moiety of the MTP plate to serve as a binding platform for bioconjugation of EDC-activated anti-HFA antibody (Ab) via carbodiimide coupling. The one-step kinetics-based sandwich enzyme-linked immunosorbent assay (ELISA) enabled the detection of HFA in 30min with a limit of detection (LOD) and a linear range of 0.02ngmL−1 and 1–243ngmL−1, respectively. It detected HFA spiked in diluted human whole blood and serum, and HFA in ethylenediaminetetraacetic acid (EDTA)-plasma of patients with high precision similar to that of conventional ELISA. The anti-HFA Ab-bound agarose-functionalized MTPs retained their functional activity after 6 weeks of storage in 0.1M PBS, pH 7.4 at 4°C.

Association of Human Fetuin-A rs4917 Polymorphism With Obesity in 2 Cohorts

BackgroundPrevious studies have shown association of the multifunctional hepatic protein α2HS-glycoprotein/human fetuin A with insulin resistance, type 2 diabetes mellitus, metabolic syndrome, obesity, and atherosclerosis. Reports of contribution of α2HS-glycoprotein/human...

Serum fetuin-A levels in subjects with and without choroid plexus calcification

Choroid plexus is an intraventricular plexus of tissue which is responsible for secretion of cerebrospinal fluid. Calcification of choroid plexus is found to be associated with age and gender. One of novel and popular glycoprotein that involves in inhibition of mineralization is human fetuin-A. In our study, we investigated plasma levels of fetuin-A in subjects with and without choroid plexus calcification. For this purpose, 41 subjects with choroid plexus calcification and 41 age and gender matched subjects with normal appearing choroid plexus were recruited. Calcified and normal choroid plexus tissue identified on computed tomography images. Overnight fasting venous blood samples were collected to measure serum fetuin-A levels using a human fetuin-A enzyme-linked immunosorbent assay kit. Statistically significant difference concerning the median concentration of fetuin-A was found between subjects with and without choroid plexus calcification (p: 0.040). Significance was also present between male subgroups (p: 0.017) and 18–27 years age subgroups (p: 0.025). Our results suggest that fetuin-A has an potent role in calcification process of choroid plexus.

Rapid sandwich ELISA-based in vitro diagnostic procedure for the highly-sensitive detection of human fetuin A

A rapid sandwich enzyme-linked immunosorbent assay (ELISA)-based in vitro diagnostic (IVD) procedure has been developed for human fetuin A (HFA), an important disease biomarker for inflammatory diseases as well as malignancies. In this simplified and cost-effective procedure, the EDC-activated anti-HFA antibody (Ab) was admixed with 1% (v/v) 3-aminopropyltriethoxysilane (APTES) in 1:1 (v/v) and dispensed in a KOH-pretreated microtiter plate (MTP). APTES formed a stable complex with the capture antibody that was in turn covalently bonded on the KOH-treated surface in 30min. The resulting immunoassay (IA) format detects HFA with a dynamic range of 0.1–243ngmL−1, and a limit of detection (LOD) and analytical sensitivity of 0.3ngmL−1 and 1.0ngmL−1, respectively. For the determination of HFA spiked in diluted human whole blood and serum, and HFA in ethylenediaminetetraacetic acid (EDTA)-plasma of patients, the obtained analytical precision is similar to that of the conventional sandwich ELISA. The anti-HFA Ab-bound MTPs, stored at 4°C in 0.1M PBS, pH 7.4, retained its biological activity for 8 weeks, thereby demonstrating excellent storage stability. This generic sandwich ELISA procedure can be extended for rapid, simplified and cost-effective detection of other disease biomarkers.

One-step antibody immobilization-based rapid and highly-sensitive sandwich ELISA procedure for potential in vitro diagnostics

An improved enzyme-linked immunosorbent (ELISA) assay using one-step antibody immobilization has been developed for the detection of human fetuin A (HFA), a specific biomarker for atherosclerosis and hepatocellular carcinoma. The anti-HFA formed a stable complex with 3-aminopropyltriethoxysilane (APTES) by ionic and hydrophobic interactions. The complex adsorbed on microtiter plates exhibited a detection range of 4.9 pg mL−1 to 20 ng mL−1 HFA, with a limit of detection of 7 pg mL−1. Furthermore, an analytical sensitivity of 10 pg mL−1 was achieved, representing a 51-fold increase in sensitivity over the commercial sandwich ELISA kit. The results obtained for HFA spiked in diluted human whole blood and plasma showed the same precision as the commercial kit. When stored at 4°C in 0.1 M phosphate-buffered saline (PBS, pH 7.4), the anti-HFA bound microtiter plates displayed no significant decrease in their functional activity after two months. The new ELISA procedure was extended for the detection of C-reactive protein, human albumin and human lipocalin-2 with excellent analytical performance.

Surface plasmon resonance-based immunoassay for human fetuin A

This article describes a highly-sensitive surface plasmon resonance (SPR)-based immunoassay (IA) for human fetuin A (HFA), a specific biomarker for atherosclerosis and hepatocellular carcinoma. The assay is based on a novel immobilization procedure that simply involves the dilution of an anti-HFA capture antibody (Ab) in 1% (v/v) 3-aminopropyltriethoxysilane (APTES), followed by its dispensing on a KOH-treated gold (Au)-coated SPR chip and incubation for 30 min. The developed SPR IA detected 0.3-20 ng mL(-1) of HFA with a limit of detection and sensitivity of 0.7 ng mL(-1) and 1 ng mL(-1), respectively. The highly-simplified Ab immobilization procedure is also 5-fold more rapid than conventional procedures. It leads to the leach-proof binding of the capture Ab, which means that the developed SPR IA is highly cost-effective, as the Ab-bound SPR chip could be reused for many repeated HFA IAs after regeneration with 10 mM glycine-HCl, pH 2.0. The Ab-bound SPR chip, stored at 4 °C, lost only 18% of its original activity after 4 months. For the detection of HFA spiked in diluted human whole blood and plasma, the results obtained by the developed SPR IA agreed well with the commercial HFA sandwich ELISA.

Surface Regeneration of Gold-Coated Chip for Highly-Reproducible Surface Plasmon Resonance Immunoassays

We developed a simple procedure for the complete regeneration of silane-grafted gold surface. This method allowed the reuse of the regenerated gold chip for custom refunctionalization. In addition, we performed highly reproducible immunoassays using these chips over several cycles. The developed procedure was optimized and comprised of consecutive treatments of functionalized Au chip with 12 M HCl for 10 min and 29 W oxygen (O2)- plasma for 5 min. Monitoring and surface characterization of the developed methodology was performed with ellipsometry and Rutherford back scattering. The developed procedure was demonstrated on SPR-based Human Fetuin A (HFA) immunoassay, where the amino groups of APTES-functionalized Au chip were cross linked to the carboxyl groups of anti-HFA antibody using 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride and sulfo- N-hydroxy succinimide. The APTES-functionalization, anti-HFA antibody immobilization and HFA binding on the regenerated SPR Au chip were highly reproducible over 40 HFA immunoassay cycles.

A sub-picogram sensitive rapid chemiluminescent immunoassay for the detection of human fetuin A

A sub-picogram sensitive chemiluminescent immunoassay (CIA) was developed for the detection of human fetuin A (HFA), a specific biomarker for hepatocellular carcinoma and atherosclerosis. The anti-HFA antibody was covalently bound to 3-aminopropyltriethoxysilane-functionalized 96-well chemiluminescent microtiter plates (MTP) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysulfosuccinimide. The developed CIA detected HFA in the range of 0.3pgmL−1–20ngmL−1 with an analytical sensitivity of 5pgmL−1, which was 125-fold more sensitive than that of commercial enzyme linked immunosorbent assay (ELISA). It is the most sensitive immunoassay for HFA detection. The overall immunoassay duration was reduced significantly by more than 3-fold in comparison to that of commercial ELISA. The anti-HFA antibody-bound MTPs, stored at 4°C in 0.1M PBS, were highly stable and did not show any significant decrease in functional activity for six months. The perfect correlation between the developed CIA and commercial ELISA for the detection of various concentrations of HFA spiked in diluted human plasma further demonstrates the potential utility of the developed HFA CIA for clinical diagnosis.

A method for regenerating gold surface for prolonged reuse of gold-coated surface plasmon resonance chip

We developed a method to completely regenerate the gold (Au) surface of 3-aminopropyltriethoxysilane (APTES)-functionalized Au-coated surface plasmon resonance (SPR) chip that had been used for human fetuin A (HFA) immunoassay. It involved treatment of the used SPR chip with freshly prepared piranha solution (concentrated H2SO4/30% H2O2=3:1, v/v) for 15min followed by extensive rinsing with ethanol and deionized water. The developed method enabled prolonged reuse of the regenerated SPR chip that increased its cost-effectiveness without affecting the reproducibility of HFA immunoassays.

Fetuin-A levels in obesity: differences in relation to metabolic syndrome and correlation with clinical and laboratory variables

IntroductionFetuin-A is an important player in the enhancement of insulin resistance. There are very limited data available concerning the relationships between fetuin-A, weight status and features of the metabolic syndrome (Met S) in obese Egyptian subjects, and especially in children. The aim of the study was to evaluate fetuin-A serum level in subjects with obesity and its possible association with other laboratory and clinical variables.Material and methodsA total of 140 obese subjects and 50 controls aged 10-40 years were recruited. Demographic, anthropometric and biochemical features were collected according to a standard protocol. Serum fetuin-A levels were measured using ELISA and the modified Third Report of the National Cholesterol Education Program (NCEP-ATP III) criteria were adopted to diagnose Met S.ResultsA higher level of serum fetuin-A was detected in obese subjects. Met S cases were also significantly associated with higher serum fetuin-A. Fetuin-A correlated significantly with BMI (r = 0.437), systolic (r = 0.228) and diastolic blood pressure (r = 0.295), waist circumference (r = 0.332), insulin resistance calculated by the homeostasis model (HOMA-IR) (r = 0.295) and high-density lipoprotein (HDL) (r = 0.362).ConclusionsFetuin-A levels were higher in adults and children with obesity and Met S. They were related to insulin resistance and to features of the Met S in cross-sectional analyses. Our study demonstrates a novel association between human fetuin-A and the Met S among obese subject. Therefore, fetuin-A might be a new promising link between obesity and its comorbidities.

Effect of antibody immobilization strategies on the analytical performance of a surface plasmon resonance-based immunoassay

Antibody immobilization strategies (random, covalent, orientated and combinations of each) were examined to determine their performance in a surface plasmon resonance-based immunoassay using human fetuin A (HFA) as the model antigen system. The random antibody immobilization strategy selected was based on passive adsorption of anti-HFA antibody on 3-aminopropyltriethoxysilane (APTES)-functionalized gold (Au) chips. The covalent strategy employed covalent crosslinking of anti-HFA antibody on APTES-functionalized chips using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide (EDC) and sulfo-N-hydroxysuccinimide (SNHS). The orientation strategy used passive adsorption of protein A (PrA) on Au chips, with subsequent binding of the anti-HFA antibody in an orientated fashion via its fragment crystallisable (Fc) region. In the covalent-orientated strategy, PrA was first bound covalently, to the surface, which in turn, then binds the anti-HFA antibody in an orientated manner. Finally, in the most widely used strategy, covalent binding of anti-HFA antibody to carboxymethyldextran (CM5-dextran) was employed. This immobilization strategy gave the highest anti-HFA antibody immobilization density, whereas the highest HFA response was obtained with the covalent-orientated immobilization strategy. Therefore, the covalent-orientated strategy was the best for SPR-based HFA immunoassay and can detect 0.6-20.0 ng/mL of HFA in less than 10 min.

Fetuin-A (α2HS-Glycoprotein) Is a Major Serum Adhesive Protein That Mediates Growth Signaling in Breast Tumor Cells

Fetuin-A (α2HS-Glycoprotein) Is a Major Serum Adhesive Protein That Mediates Growth Signaling in Breast Tumor Cells