DLEU2 and B-cell chronic lymphocytic leukemia: Deletions of the Dleu2/Mirc30 locus, which encodes miR-15a and miR-16–1, occur in more than 50% of human chronic lymphocytic leukemia (CLL) cases (Calin et al., 2002), and targeted deletion of these miRNAs in mice induces a CLL-like indolent B lymphocyte proliferative disease (Klein et al., 2010).