RIPK2 (RIP2; RICK) is a death domain-containing protein kinase. Inohara identified cDNAs encoding a predicted 540-amino acid protein RICK, which contains an N-terminal serine/threonine kinase catalytic domain and a C-terminal caspase activation and recruitment domain. Inohara also demonstrated that RICK is a novel kinase that may regulate apoptosis induced by the FAS receptor pathway (1). McCarthy found that overexpression of RIP2 signaled both cell death and NF-kappa-B activation (2). Thome reported that RICK specifically interacted with the CARD of ICE/caspase-1, and this interaction correlated with the processing of pro-caspase-1 and the formation of the active caspase-1 p20 (3). Chin generated Ripk2-deficient mice and concluded that RIP