Fig. (3) Kinetics of OATP1B1- and OATP1B3-mediated FMTX uptake. Uptake of increasing concentrations of FMTX was measured at 37 ^°C for 2 min on 24-well plates with CHO wild-type and OATP1B1 or OATP1B3 expressing cells. Net OATP1B1 (open circles) or OATP1B3 (closed circles) uptake was calculated by subtracting uptake into wild-type cells from uptake into OATP-expressing cells. The values (means ± SE) were fitted to the Michaelis-Menten equation using non-linear regression analysis.