miR-15a can decrease endogenous c-Myb protein levels in K562 cells. (A) K562 cells were transfected with 50-nM concentration of a given RNA oligonucleotide. Forty-eight hours after transfection, c-Myb protein Western blot analysis was performed with cell lysates obtained from the transfected K562 cells. (B) Quantitative real-time PCR (QRT-PCR) assay performed on RNA isolated from K562 cells transfected with the indicated RNA oligonucleotide molecules. Data are presented as a function of c-myb mRNA copies relative to GAPDH mRNA. Mock (control) cells were subjected to nucleoporation, but in the absence of RNA. The mean c-myb mRNA level are from 3 independent transfection experiments. (C) K562 cells were transfected with 100 nM has-miR-15a inhibitor (miR-15a-In) or miR inhibitor negative control (miR-In-Control). Forty-eight hours after transfection, c-Myb protein Western blot analysis was carried out using cell lysates from the transfected K562 cells. (D) Detection of the expression of miR-15a in K562 cells using mirVana qRT-PCR primer set (Ambion) according the manufacturer's instructions.