In chronic lymphocytic leukemia (CLL), B-cell expression of microRNAs (miR15 and miR16), which are required for normal CD5+ B-cell differentiation, was significantly downregulated or absent due to 13q14 locus allelic loss, which was observed in 68% of all CLL cases [10]. Here, CD5 is linked to B-cell chronic lymphocytic leukemia.