Antiapoptotic protein which protects cells uniquely from Fas-induced apoptosis. Regulates Fas-mediated apoptosis in neurons by interfering with caspase-8 activation. May play a role in cerebellar development by affecting cerebellar size, internal granular layer (IGL) thickness, and Purkinje cell (PC) development. Interacts with FAS/TNFRSF6 and BAX. Highly expressed in breast carcinoma tissues. Enhanced expression correlates with the grade of the tumor (grade II/grade III) in primary breast tumors (at protein level). Widely expressed. Expressed at high levels in the brain especially in the hippocampus. Regulated by the AKT1/LEF1 pathway in breast cancer cell lines. Belongs to the BI1 family. LFG subfamily. Extended N-terminus.