The concentration-dependent accumulation of (A) [3H]-E217βG (0.1–40 µM, 2 min) mediated by OATP1B1 and (B) [3H]-CCK-8 (0.1–40 µM, 3 min)-mediated by OATP1B3 in HEK293-OATP1B1 and –OATP1B3 cells pre-incubated with vehicle CTL, EVR (1 µM, 1 h), or SIR (1 µM, 1 h). Values of [3H]E217βG accumulation in Mock cells were subtracted from those in HEK293-OATP1B1 cells. Vmax and Km values were determined as described in the Material and Methods. Solid, dashed line, and dotted line represent the best fits of the Michaelis–Menten equation to the data of CTL (closed circles), EVR (open circles), or SIR pre-incubation (open triangles), respectively. Data represent the mean ± SD of a representative graph of three and 5 independent experiments for OATP1B1 and OATP1B3, respectively, in triplicate.