Transport of imatinib across transfected MDCK monolayers. MDCK monolayers were incubated with transport media with or without imatinib and transport inhibitors. The transport of ¹⁴C-labeled imatinib was measured every 30 minutes for 3 hours in the apical-basolateral (A-B, •) and the basolateral-apical (B-A, ▪) directions. A transport inhibitor, PSC-833 (10 μM), was included (□) in the media of the (B) MDR1-transfected monolayers but not in the (A) nontransfected parental cell line. Data represent mean ± SEM from 4 to 6 separate monolayers.