Deciphering the pathways of life and death.

Caspase recruitment and oligomerization mediated by adaptor proteins constitute a basic mechanism of caspase activation. The complex phenotypes of the caspase knockout mice indicate that multiple mechanisms of caspase activation operate in parallel and that death signal transduction pathways are both cell-type and stimulus specific. The BH3-domain- containing pro-apototic members of Bcl-2 family may be one of the critical links between the initial death signals and the central machinery of apoptosis.