Fas-associated phosphatase-1 (FAP-1), a NT7 non-receptor protein tyrosine phosphatase, is comprised of a N-terminal FERM domain, five PDZ domains, and a C-terminal tyrosine phosphatase domain. The protein has been shown to bind the cytosolic tail of Fas (Apo1, CD95) and regulate Fas-induced apoptosis. Human tumor cell lines become resistant to Fas-mediated apoptosis when transfected with FAP-1, indicating that FAP-1 functions as a negative regulator in Fas-mediated death signaling. FAS resistance has been documented in a variety of cancers, including cancer of the lung, ovary, pancreas, and liver. At least three protein isoforms of FAP-1 have been reported. Alterations in FAP-1 expression have been shown to result in defects in cytokinesis.Synonyms: FAP1, Fas-associated protein-tyrosine phosphatase 1, PNP1, PTP-BAS, PTP-E1, PTP1E, PTPL1, Protein-tyrosine phosphatase 1E, Protein-tyrosine phosphatase PTPL1, Tyrosine-protein phosphatase non-receptor type 13