Figure 2.

Different forms of evasion from mitochondrial apoptosis. Three distinct scenarios are depicted. In cancers such as chronic lymphocytic leukemia, large amounts of pro-apoptotic activators are sequestered (i.e., high priming) by a single anti-apoptotic relative. In other hematologic cancers (e.g., B-cell acute lymphoblastic leukemia), apoptotic priming is high, but the pro-apoptotics are concurrently sequestered by multiple anti-apoptotic relatives (e.g., BCL-2, MCL-1 and BCL-xL). In solid tumors, pro-apoptotic members are mostly not bound to the anti-apoptotic proteins, and hence sensitivity to BH3 mimetics is generally low. CLL: chronic lymphocytic leukemia; B-ALL: B-cell acute lymphoblastic leukemia.