Efflux of dasatinib and imatinib by ABCB1. Efflux of dasatinib (A,B) and imatinib (C,D) in MDCKII-transfected (A,C) and MDCKII-ABCB1–transfected (B,D) cells. ▴ indicates A-B (apical to basal transport); ■, B-A (basal to apical transport); ♦, A-B + PSC833; and ×, B-A + PSC833. There was significantly increased transport of both drugs in the B-A direction in comparison with A-B (P = .001 for dasatinib and P < .001 for imatinib). This effect is abolished by PSC833 for each drug, indicating that they are both effluxed by ABCB1 (P = .001 for dasatinib and P < .001 for imatinib). Data represent mean plus or minus SEM from 3 to 4 separate monolayers.