Figure 4.

The apoptotic cascade. The two major apoptotic pathways, the extrinsic one (the death receptor pathway) and the intrinsic one (the mitochondrial pathway) are shown schematically. All the major proteolytic (black) and non-proteolytic steps (magenta) are marked with arrows, whereas the proteases (caspases and cathepsins) are shown in white characters in dark grey field. The lysosomal amplification loop is also marked, although the link between mitochondria and lysosomes has not been established yet. The direct destabilization of lysosomes (marked with a lightning) seems the only way that the lysosomes destabilization can trigger the apoptotic cascade, although it also ends up in self-amplification through the engagement of the mitochondrial pathway.