Effect of inhibitors of hOCT1 and ABCB1 on drug uptake by KCL22 cell lines. The effect of hOCT1 inhibitors (verapamil, amantadine, prazosin) and ABCB1 inhibitors (PSC833, tariquidar) on the uptake of radiolabeled dasatinib (A) and imatinib (B) into mock-transfected KCL22 cells () and into high hOCT1-expressing cells (■) was examined (t = 30 minutes). No statistically significant effect was seen for inhibiting dasatinib uptake into either cell line (P = NS for all inhibitors in both cell lines). In contrast, all inhibitors significantly inhibited imatinib uptake (P < .005 for all 3 blockers for both cell lines). Under conditions with no inhibitor present, there was a significant difference on the uptake of drugs between hOCT1-expressing and mock-transfected cells with P = .004 for dasatinib and P = .005 for imatinib. Blockade of ABCB1 by PSC833 and tariquidar resulted in both cell lines showing similar levels of intracellular drugs. Data represent mean plus or minus SEM from 4 to 6 replicate experiments.