Caspases are a family of evolutionarily conserved cysteine proteases that 
constitute the effector arm of the apoptotic machinery. Studies in 
Caenorhabditis elegans, Drosophila melanogaster, and mouse point to 
evolutionarily conserved caspase function in developmentally programmed cell 
death in metazoans. Whereas in the nematode all developmental cell death is 
mediated by a single caspase, in Drosophila and the mouse some caspases appear 
to regulate cell death in a spatio-temporally restricted manner. This article 
reviews what we currently know about the roles of various caspases in the 
execution of developmentally programmed cell death and what may be expected from 
future research in this field.