Apoptosis is regulated by death domain (DD) and/or caspase recruitment domain (CARD) containing molecules and a caspase family of proteases. CARD domain containing cell death regulators include RAIDD, Apaf-1, caspase-9, and caspase-2. A novel CARD domain containing protein was recently identified and designated ARC for apoptosis repressor with CARD. ARC interacts with caspase-2 and -8 and inhibits enzymatic activity of caspase-8. ARC suppresses apoptosis induced by cell death adapters FADD and TRADD and by cell death receptors Fas, TNFR-1 and DR3. The messenger RNA of ARC is primarily expressed in skeletal muscle and cardiac tissue.