Fig. 2. The main steps in the activation of intrinsic apoptosis (see text for detailed description). The red rectangles indicate the steps that involve binding and, therefore, are likely to be enhanced by hyperosmolarity: 1 - interaction between BH3-only proteins, BCL-2 family proteins, and BAX; 2 - insertion of BAX into the outer mitochondrial membrane; 3 - oligomerization of BAX within the membrane; 3 - binding of cytochrome c to monomeric Apaf-1; 4 - apoptosome formation; 5 - dimerization of caspase-9.