Caspase-1 molecule. Computer artwork showing the secondary structure of a molecule of caspase-1. Caspase-1 is a protease, an enzyme that cleaves proteins. It is found predominantly in the cell cytoplasm, where it activates interleukin-1-beta, a molecule that mediates immune and inflammatory responses. Due to this activity caspase-1 is also known as ICE (interleukin-1-beta converting enzyme). Like other caspases it also plays a role in apoptosis (programmed cell death), but only when over-expressed.