Since our initial data identified BCL-XL as a critical survival factor in CML cell lines, we used a toolkit of selective BCL-2 family inhibitors, comprising ABT-737 (BCL-2, BCL-XL and BCL-w-specific inhibitor), ABT-199 (BCL-2-selective), A-1331852 (BCL-XL-specific) and A-1210477 (MCL-1-selective) to further evaluate the role of BCL-XL in CML cell survival. Here, MCL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.