BCL2 and neoplasm: Since different BH3-mimetic drugs target different anti-apoptotic Bcl-2 proteins and the Bcl-2 proteins are known to be functionally redundant [37,38,39], any rational attempt to inhibit these proteins must ideally begin by understanding which of the anti-apoptotic Bcl-2 proteins are expressed in a given tumor type, in a given patient, and under which circumstances.