This antibody recognizes FAP-1, including FAP-1 isoforms; FAP-1 (also known as Fas-associated phosphatase-1, PTPN13, PTP-BAS, hPTPIE, and PTPL1) is a member of the protein tyrosine phosphatase (PTP) family FAP-1 phosphatase is thought to be important in the Fas signaling pathway. FAP-1 binds to the cytosolic tail of the Fas receptor (Apo1, CD95) and inhibits Fas-induced apoptosis. Increased FAP-1 protein levels in some tumor cell lines and tumor tissues correlates with resistance to Fas-mediated apoptosis. In general, FAP-1 expression has been found to be highest in cell lines and tissues that are relatively resistant to Fas-mediated apoptosis. Gene transfer-mediated elevations in FAP-1 partially abolished Fas-induced apoptosis in a T cell line which is consistent with an inhibitory effect of FAP-1 on Fas signal transductions. Additionally, FAP-1 expression correlates with Fas resistant in ovarian cancer cell lines and FAP-1 is commonly expression in ovarian cancers.