The caspase cascade is tightly regulated by various proteins to ensure controlled cell death. For example, the Bcl-2 family of proteins regulates the intrinsic pathway by controlling mitochondrial outer membrane permeabilization. Inhibitors of apoptosis proteins (IAPs) can directly inhibit caspases, thus preventing apoptosis. Conversely, Smac/DIABLO and Omi/HtrA2 can neutralize IAPs, promoting apoptosis.
