Death by design: mechanism and control of apoptosis

Active cellular suicide by apoptosis plays important roles in animal develo pment, tissue homeostasis and a wide variety of diseases, including cancer, AIDS, stroke and many neurodegenerative disorders. A central step in the e xecution of apoptosis is the activation of an unusual class of cysteine pro teases, termed caspases, that are widely expressed as inactive zymogens. Or iginally, the mechanisms for regulating the caspase-based cell death progra mme seemed to be different in Caenorhabditis elegans, mammals and insects. However, recent results suggest that these apparent differences in the cont rol of cell death reflect our incomplete knowledge, rather than genuine mec hanistic differences between different organisms.