This short video illustrates key steps in Caspase-mediated formation and activation of the apoptosome. Cytochrome c release from the mitochondrion during apoptosis leads to amplification of the caspase signaling cascade via formation of the apoptosome. A radially-symmetric structure, the apoptosome assembles upon binding of cytochrome c (blue) to Apaf-1 (beige), followed by recruitment of caspase-9 (red). Once assembled, the apoptosome's activated caspase-9 cleaves and activates cytosolic caspase-3 (red, floating) and rapidly amplifies the caspase cascade. This leads to the destruction of numerous intracellular targets by caspase-3 including the actin cytoskeleton (green).