Overexpression of miR-181a in chronic myeloid leukemia K562 cells enhanced the chemotherapeutic sensitivity of these cells to the drug imatinib. (A) The overexpression of miR-181a in K562 cells infected with a lentivirus carrying the miR-181a gene was confirmed by reverse transcription-quantitative polymerase chain reaction analysis. K562 cells infected with a lentivirus carrying EGFP were used as negative control. (B) The overexpression of miR-181a in the K562 cells enhanced the inhibitory effect of the chemotherapeutic drug imatinib on the viability of these cells (P