MCL1 and B-cell chronic lymphocytic leukemia: Previously we reported an upregulation of pro-survival Bcl-2 family members in the LN of patients with CLL [6, 34], which correlated with increased expression of Bcl-XL and Mcl-1 in the LN ‘emigrant’ versus ‘immigrant’ fraction of circulating CLL cells, defined by opposing expression levels of CD5 and CXCR4.