sentence1: The Bcl-2 inhibitor ABT-737 induces regression of solid tumors  and its derivatives are in the early clinical phase as cancer therapeutics; however, it targets Bcl-2, Bcl-XL, and Bcl-w, but not Mcl-1, which induces resistance against apoptotic cell death triggered by ABT-737.
sentence2: Recently, it has been reported that ABT-737 is not cytotoxic to all tumors cells, and that chemoresistance to ABT-737 is dependent on appreciable levels of Mcl-1 expression, the one Bcl-2 family member it does not effectively inhibit.