Besides, Noxa-inducing agents have also been reported to sensitize cancer cells to ABT-737, including Bortezomib [10], Fludarabine [11], Oxaliplatin [12], etc. Recently, Dai Y et al demonstrated that Celastrol, a natural extract with potent anti-cancer capabilities, could lead to induction of Noxa and cleavage of Mcl-1 [13], which attracted our attention to examine the effects when combine this agent with ABT-737, whose anti-cancer activities were closely related to Mcl-1. This evidence concerns the gene PMAIP1 and cancer.