Effect of OCT inhibitors on imatinib uptake by CEM cells. (A) Verapamil, a P-glycoprotein and hOCT1 inhibitor, decreased imatinib uptake. (B) Amantadine and (C) procainamide, both hOCT1 and hOCT2 inhibitors, also decreased imatinib uptake. (D) Prazosin, an hOCT1 and hOCT3 inhibitor, decreased imatinib uptake. (E) The hOCT3 inhibitor corticosterone had no effect on imatinib uptake. (F) N-methylnicotinamide, an hOCT2 inhibitor, had no effect on imatinib uptake. Data are presented as mean plus or minus SEM of 4 observations. ^*Significantly different from control (P < .05). ^**Significantly different from control (P < .01).