Fig. 1. Events regulated by Hsps in the mitochondrial or `intrinsic' apoptotic pathway. Extracellular signals or stresses converge to regulate the mitochondria-mediated pathway to caspase activation and cell death. Heat shock proteins intervene at multiple points within this pathway both upstream (A) and downstream (B) of the associated mitochondrial changes to regulate the engagement and/or progression of apoptotic events. Hsp-mediated inhibition is indicated (T-bars) and Hsp-mediated potentiation of a signaling pathway is depicted as a direct interaction between the Hsp and its target (+).