PDCD4 and B-cell chronic lymphocytic leukemia: For example, overexpression of the oncogene, miR-21, frequently highly expressed in solid and hematologic malignancies, represses strong tumor suppressors as PTEN or programed cell death 4 (PDCD4) while loss of the tumor-suppressor miR-15a/miR-16-1 in CLL induces the overexpression of the anti-apoptotic BCL2 (Cimmino et al., 2005; Meng et al., 2007; Asangani et al., 2008).