Apoptosis regulator. Has anti-apoptotic activity, both for apoptosis triggered via death-receptors and via mitochondrial factors. Interacts with CASP8, BCL2 and BCL2L1 through SAM domain and also with HIP1, IFT57, ESRRBL1 and BCAP31. Expressed highly in brain, moderately in small intestine, weakly in testes and only faintly in liver and skeletal muscle. Not expressed in heart, kidney, lung and spleen.