Transport of Cbl metabolites by MRP1 in vesicular transport experiments. (A) Time course experiments of control and MRP1-containing vesicles incubated with 100nM [⁵⁷Co]-OH-Cbl. (B) Concentration-dependent transport of [⁵⁷Co]-OH-Cbl in MRP1-containing vesicles. (C) Inhibition of MRP1-mediated transport of 1μM [³H]-E₂17βG by various concentrations of unlabeled GS-Cbl, OH-Cbl, and CN-Cbl, as indicated. (D) Concentration-dependent transport of [3H]-E₂17βG in MRP1-containing membrane vesicles in the presence or absence of the indicated concentrations of GS-Cbl. (E) Lineweaver-Burk transformations of the data presented in panel D. Each data point represents the means ± 1 SD of an experiment performed in triplicate. MRP1-dependent transport was calculated by subtracting ATP-dependent transport in control vesicles from ATP-dependent transport in MRP1-containing vesicles.