ICEBERG, an inhibitor of pro-caspase-1 activation, consists essentially of only a CARD. It inhibits generation of IL-1b by interacting with caspase-1 and preventing association with RIP2. The ICEBERG functions as a competitive antagonist of RIP2/pro-caspase-1 interactions and inhibits caspase-1-dependent pro-L-1b secretion in mononuclear cells. ICEBERG is induced by proinflammatory stimuli, suggesting that it may be part of a negative feedback loop.