Receptor-interacting serine/threonine-protein kinase 2 is a member of the receptor-interacting protein (RIP) family of serine/threonine protein kinases. The encoded protein contains a C-terminal caspase recruitment domain (CARD), and is a component of signaling complexes in both the innate and adaptive immune pathways. It is a potent activator of NF-kappa;B and inducer of apoptosis in response to various stimuli. Expression of RICK promoted the activation of caspase-8 and potentiated apoptosis induced by FAS, FADD, CLARP, and caspase-8. Northern blot analysis revealed that RICK is expressed in various human tissues as 2.5- and 1.8-kb mRNAs that differ due to alternative polyadenylation. The authors concluded that RICK is a novel kinase that may regulate apoptosis induced by the FAS receptor pathway.