Abstract Disclosure: N. Mukherjee: None. R. Ballesteros: None. A. Mukherjee: None. TGFβ family ligands play crucial roles in promoting cellular proliferation. Moreover, activin and TGFβ are linked with cancer. Deletion of FSTL3, an inhibitor of a subset of TGFβ ligands, in mice leads to increased proliferation in all tissues investigated including the testis. We also find increased SMAD2/3 activation in FSTL3 knockout (KO) compared to wildtype (WT) in these tissues. Therefore, the FSTL3 KO mouse is a model of increased activity of endogenous TGFβ ligands that are inhibited by FSTL3, such as activin. It is likely that increased signalling by these ligands leads to the observed increased cellular proliferation in FSTL3 KO mice. To discover genes that might be involved in activin-dependent mitosis, we studied gene expression datasets linked to cellular proliferation. We hypothesised that genes important in cellular proliferation will be downregulated in senescent cells and upregulated in models of increased cellular proliferation and activin action such as the FSTL3 KO mice. We queried GEO datasets to identify studies related to senescence and selected Hutchinson-Gilford progeria syndrome (HGPS): fibroblast (HG-U133A), GSE3860. We found 4048 transcripts showing significantly (p<0.05) altered expression in HGPS fibroblasts compared to WT. We developed a Python-based program, “WordMiner”, that inputs a keyword and a list of terms (e.g. genes) and then searches a specified database sequentially for publications including the keyword and each term. The output is a table of search result frequencies and hyperlinks to the search result pages, compiled in an auxiliary file, produced with greater speed and efficiency than manual search methods. The greater the search result frequency, the stronger the known link between the keyword and the term. We used WordMiner to query the association of the search term “mitosis” with the 4048 genes above using PubMed as the database and identified 1235 transcripts. We refined this list further using the keyword “activin” to identify 420 transcripts linked to activin and mitosis. Importantly, by comparing against our RNAseq data, we find 20 of these genes upregulated in the FSTL3 KO postnatal day 3 transcriptome. This finding supports our hypothesis, and also demonstrates WordMiner as an efficient and versatile cross-referencing query tool. Among the 20 genes identified are transcripts known to be important in proliferation, such as Akap9 and Wnt2b. These and the remainder in the list of genes highlighted are therefore likely to be involved in pathways induced by activin, promoting cellular proliferation in FSTL3 KO testis. Currently, siRNA transfection experiments are underway to address whether knockdown of these genes in a Sertoli cell line (TM4) limits proliferation. This will help in the elucidation of the molecular pathways involved in postnatal Sertoli cell proliferation. Presentation: 6/3/2024