Two apoptotic cell-death pathways exist in mammals — a cell-intrinsic pathway and a cell-extrinsic pathway — and these distinct pathways converge with the activation of the caspase cascade.

where it bound to a caspase-activating protein, Apaf-1. But "it was not clear which of the 12 human caspases were recruited by Apaf-1," Martin recalls. There was an exciting suspicion that they formed ...