Caspases and caspase inhibitors.

Five years ago, little was known about mechanisms of apoptotic execution. Now, one class of cell-death gene, the cysteine and aspartases (caspases) has come under intensive study. This review discusses the two classes of caspases, the reasons why humans may have so many caspase genes, the growing list of caspase substrates, and viral and pharmacological caspase inhibitors.