Apoptosis is regulated by death domain (DD) and/or caspase recruitment domain (CARD) containing molecules and a caspase family of proteases. CARD containing cell death regulators include RAIDD, RICK, Bcl10, Apaf-1, ARC, caspase-2 and caspase-9. A novel CARD domain containing protein has been identified in human and mouse and designated ASC and TMS1. Irregular expression of ASC/TMS1 induced apoptosis through activation of caspase-9 and inhibited the survival of human breast cancer cells. Overexpression of ASC/TMS1 induced DNA fragmentation. ASC/TMS1 is expressed in a variety of human and mouse tissues.