3.3. Up-Regulation of miR-26b-5p in Progressive U-CLL Is Associated with Decreased Expression and Nuclear Localization of SMAD-4, Down-Modulation of p21−Cip1 Cell Cycle Marker, and Up-Regulation of c-Myc Oncogene. This evidence concerns the gene CDKN1A and B-cell chronic lymphocytic leukemia.