APIP is an APAF1 (MIM 602233)-interacting protein that acts as a negative regulator of ischemic/hypoxic injury.The protein highly expressed in skeletal muscle and heart and binds to the CARD of Apaf-1 in competition with caspase-9. Exogenous APIP inhibits cytochrome c-induced activation of caspase-3 and caspase-9, and suppresses cell death triggered by mitochondrial apoptotic stimuli through inhibiting the downstream activity of cytochrome c released from mitochondria.