All BH3-only proteins contain only one domain in common called α-helical BH3 domain.10 This conserved BH3 domain has been demonstrated to play a crucial role in cancer therapy.80, 81, 82 This pathway is triggered by three subgroups of BCL-2 protein family: BH3 (BCL-2 homology 3)-only proteins, BCL-2, BCL-2-associated X protein (BAX) and BCL-2 antagonist/killer (BAK), which interact with each other on the mitochondrial outer membrane. The gene discussed is BCL2; the disease is cancer.