The most prominent anti-apoptotic bcl-2 family members, including bcl-2 (B-cell CLL/lymphoma 2), bcl-XL (BCL2L1) and mcl-1 (myeloid cell leukemia 1; BCL2L3), were originally identified and found to be over-expressed in leukemia cells [13,14]. The gene discussed is MCL1; the disease is leukemia.