MCL1 and B-cell chronic lymphocytic leukemia: To further investigate whether expression of anti-apoptotic genes, including BCL-xL, contribute to treatment free survival in CLL patients, RT-PCR was used to assess expression of the anti-apoptotic, BCL-2, MCL-1, BCL-xL, BFL-1, BCL-W, and BCL-B and pro-apoptotic, BIM, PUMA, and NOXA genes.