Figure 1.

Pathways to Apoptosis. The mitochondrial pathway is activated by BH3-only proteins, which sense cellular stress and inactivate pro-survival BCL-2 family members. This leads to the permeabilization of the outer mitochondrial membrane and the release of cyctochrom C, Apaf-1 and caspase-9. The death receptor pathway is activated by the TNF family ligands. Caspase-8 is activated by adaptor proteins including FADD. In PDAC cells, the death receptor pathway is linked to the mitochondria by the BH3-only protein Bid that is cleaved by caspase-8.