c-Myb regulates miR-15a expression. (A) Diagram indicates the c-Myb binding sites (MBS) in the miR-15a promoter, as well as the primers (arrows) used for ChIP assays. (B) ChIP assay shows c-Myb binding to miR-15a in K562 cells through Myb binding site 1. Protein-DNA complexes from K562 cells were immunoprecipitated with normal mouse IgG, antiacetylated H4 monoclonal antibody(Ac-H4) or c-Myb monoclonal antibody. Real-time PCR was performed using miR-15a promoter primers flanked c-Myb binding sites. Fold enrichment of a given DNA region was calculated as the ratio between the enrichment obtained with a specific antibody and that obtained with the normal IgG. Results are the average of 3 independent cross-linking ChIP experiments. Error bars indicate standard error. (C) c-myb siRNA down-regulate miR-15a expression in K562 cells. K562 cells were transfected with 100 nM c-myb siRNA or control siRNA. Forty-eight hours after transfection, c-myb and miR-15a expression was examined using a quantitative real-time PCR (QRT-PCR) assay performed on RNA isolated from K562 cells transfected with the indicated RNA oligonucleotide molecules. Results depicted are representative of 3 independents experiments.