CD5 and B-cell chronic lymphocytic leukemia: One key phenotype reported upon deletion of miR‐15a/16‐1 or miR‐15b/16‐2 clusters is an increase in CD5+ CLL‐like B cells in the spleen and blood of aged mice, indicating that deletion of one cluster can provoke a clear effect even in the presence of the two remaining clusters [8, 9].