Figure 2.

Mechanisms of p53-induced apoptosis. Model depicting the mechanism by which activated p53 induces apoptosis through the BCL-2-regulated pathway. Fat arrows indicate p53-induced targets that are essential for p53-induced apoptosis. Thin arrows indicate p53-induced targets that are constituents of the BCL-2-regulated apoptotic pathway but are still expressed at levels sufficient for apoptosis induction in the complete absence of p53; that is, their induction by p53 may make the pathway work more efficiently, but this induction is not a sine qua non for p53-induced apoptosis, at least in haematopoietic cells. The broken arrow indicates that p53 may also activate BIM expression indirectly. The possible scenario that activation of targets that are not constituents of the apoptosis machinery per se can impact on apoptosis indirectly is also depicted