Further studies showed that the majority of colorectal cancer cell lines with a gain in BCL2L1 are sensitive to the selective BCL-XL inhibitor A-1155463 as well as to siRNA-medited knockdown of BCL2L1. Although the gains are typically modest (3–4.4 copies), it should be noted that CN gain of other anti-apoptotic genes such as MCL1 is also modest in other tumors that nevertheless become dependent on these genes for survival [12]. This evidence concerns the gene BCL2L1 and colorectal cancer.