Interleukin-1 beta-converting enzyme (ICE) was originally identified as a novel type of cysteine protease responsible for the conversion of percursor interleukin-1 beta to mature form. ICE is also a mammalian homologue of the Caenorhabitis elegans cell death protein Ced-3. Several ICE/ced-3 family proteases have been isolated and were recently renamed "Caspase." The overexpression of those proteases induces apoptosis. Moreover, it has been reported that several types of stimuli-induced apoptosis are equally inhibited by caspase-specific inhibitors, indicating that caspase proteases are common mediators of apoptosis. During induction of apoptosis, caspase proteases are thought to be sequentially activated and cleave several cellular proteins essential for cell growth.