Apoptosis is an evolutionarily conserved form of cell suicide responsible for various biological processes including the normal turnover of cells and the proper functioning of the immune system. This process of shutting down old, diseased, or otherwise disfunctional cells is mediated by a cascade of proteolytic enzymes known as cysteine proteases, or caspases. Pro-apoptotic signals activate the enzymatic cascade resulting in the cleavage of protein substrates, leading to the disassembly of the cell (1-4). Caspases have been identified in organisms ranging from C. elegans to humans. Members of the
