FLIP, also known as CASP8 and FADD-like apoptosis regulator (CFLAR), contains two death effector domains (DEDs) and a caspase-like domain. FLIP may play a crucial role between cell survival and cell death pathway in mammalian cells and interacts with adapter protein FADD and caspase-8 and -10, and potently inhibits apoptosis induced by all known death receptors DR3 (death receptor 3), TRAIL-R (TNF-related apoptosis-inducing ligand receptor) and TNFR1 (tumor necrosis factor receptor 1).