FAP-1 (Tyrosine-protein Phosphatase Non-receptor Type 13, Fas-associated Protein-tyrosine Phosphatase 1, PTP-BAS, Protein-tyrosine Phosphatase 1E, PTP-E1, hPTPE1, Protein-tyrosine Phosphatase PTPL1, PTPN13, PNP1, PTP1E, PTPL1)

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. PTPs are enzymes that catalyze the removal of a phosphate group attached to a tyrosine residue. Most intracellular signaling involves reversible phosphorylation events; therefore, PTPs are central to the dynamic regulation of signaling cascades that underlie cell functions. For example, PTPs play key roles in regulating cell growth, differentiation, proliferation, inflammation, and oncogenic transformation. PTPs are emerging as a promising class of signaling targets for diseases such as cancer, neurodegeneration, diabetes, and inflammation. A key challenge is to identify specific PTPs that are invovled in a disease process and develop therapeutics to modulate the PTP. 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. Human Fas has a putative consensus tyrosine phosphorylation site (Tyrosine 275) suggesting that Fas surface expression or signaling may be regulated by phosphorylation. FAP-1 has been shown to directly bind to Fas and may dephosphorylate Fas as part of the down regulation of the apoptotic pathway. It is thought that development of therapeutics to inhibit FAP-1 may increase the ability of tumor cells with upregulated FAP-1 to undergo apoptosis. FAP-1 is a large ~270kD protein. Multiple alternatively spliced FAP-1 transcript variants which encode distinct proteins have been reported, including shorter forms. Please see Application Notes section for additional details on FAP-1 isoforms. Recognizes FAP-1, including FAP-1 isoforms listed in the Application Notes section. Applications: Suitable for use in Western Blot, Immunohistochemistry and Immunoprecipitation. Other applications not tested. Recommended Dilution: Western Blot: 1:1000-1:2000 Immunohistochemistry (formalin fixed paraffin embedded): 1:1000-1:5000 Immunoprecipitation: 1:50-1:200 Immunohistochemistry: Frozen Optimal dilutions to be determined by the researcher. Positive Control: Spleen, lymphoid, many cancer cell lines Storage and Stability: May be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for at least 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.