To further investigate whether KCNJ2/Kir2.1 regulates MDR, we first established two stable KCNJ2/Kir2.1-overexpressing sublines, H69-KCNJ2 and H446-KCNJ2, and suppressed KCNJ2/Kir2.1 expression in H69AR and H446AR cells by shRNAs specifically targeting KCNJ2. Next, we examined the effect of KCNJ2/Kir2.1 upregulation and downregulation on the sensitivity of SCLC cells to chemotherapeutic drugs (ADM, CDDP and VP-16). This evidence concerns the gene KCNJ2 and small cell lung carcinoma.