BCL2 and cancer: In this modus, Bcl-2 targets the mitochondria, preventing apoptosis initiation through cytochrome C release.7, 8 Some cancer cells are addicted to high Bcl-2 levels to neutralize upregulated BH3-only proteins like Bim.6, 9, 10 These cells are very sensitive to BH3-mimetic drugs like ABT-737, which compete with Bim for binding to Bcl-2, resulting in Bim release from Bcl-2 and apoptosis initiation.10, 11, 12