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. Author manuscript; available in PMC: 2010 Oct 1.
Published in final edited form as: Traffic. 2009 Jun 9;10(10):1390–1404. doi: 10.1111/j.1600-0854.2009.00951.x

Figure 1. Essential pathways to caspase activation and cell death.

Figure 1

Apoptosis is initiated by internal cellular stress or extracellularly through the binding of ligands to cell surface death receptors. Type I pathways directly activate executioner caspases through initiator caspases to result in death. In Type II pathways, death signals are routed through the Bcl-2 proteins such as Bid and the mitochondria to control the release of cytochrome c. Cytosolic cytochrome c binds Apaf-1 to activate the apoptosome and caspase-9 to result in executioner caspase-3 activation and cell death.