CLL exhibits differential miR-34a expression based on the response to DNA damage as measured by p53 and p21 induction after IR. Based on the induction of p53 and p21 protein by FACS, CLL cases were stratified into 3 groups as previously described.^18,46  Type A dysfunction (p53 defect) shows high basal p53 expression and failure to up-regulate p53 and p21 after IR. Type B defect shows normal (no) basal expression of p53 and failure to induce p53 and p21 protein expression. Since we saw a heterogeneous pattern with cases that up-regulated p53 or p21 only, but exhibited an abnormal pattern, we grouped these patients as type B* defects. In the “normal” group, no baseline expression of p21 and p53 could be detected, but both p21 and p53 were induced by IR. When we assessed miR-34a levels in these subgroups, we saw significant differences in miR-34a expression not only after IR but also at basal levels.