Caspases are key effector components of apoptosis, the process of programmed 
cell death. However, a large body of recent work has shown that caspase activity 
is necessary for several nonapoptotic cellular functions, such as proliferation, 
differentiation, survival, and the regulation of cytokine expression. In this 
review, we concentrate on the nonapoptotic functions of caspases and, in 
particular, on nonapoptotic roles of caspases in the immune system. Because of 
the involvement of caspases in promoting cell death, as well as cell 
proliferation and other nonapoptotic functions, studies involving the inhibition 
of caspases in vivo must be interpreted with caution.