ABT-737 is an inhibitor of BCL-XL (BCL2L1), BCL-w (BCL2L2), and BCL-2 that has been shown to enhance cell death, including in MCF7 breast cancer cells and myeloma cells by binding and inhibiting the activity of antiapoptotic BCL2 family members [30,31]. This evidence concerns the gene BCL2L2 and breast cancer.