Although this compound binds to both recombinant Bcl-2 and Bcl-xL with Ki values, determined in biochemical assays of <1 nM, recent data suggest that more potent and efficacious dual small-molecule inhibitors of Bcl-2 and Bcl-xL may be needed in order to successfully target tumor cells whose survival is protected by Bcl-xL alone or by both Bcl-2 and Bcl-xL. This evidence concerns the gene BCL2L1 and neoplasm.