Uptake of (A) 45 nM [3H]ES in human OATP1B1 (hOATP1B1)- and hOATP2B1-transfected HEK293 cells and (B) 60 nM [3H]E2G uptake in hOATP1B3-transfected HEK293 cells. Mock-transfected [pcDNA3.1(+) transfection] HEK293 cells were used as the negative control. Data represent the means ± SD from three or more independent experiments (n = 3) *, P < 0.05, **, P < 0.01, and ***, P < 0.001, significantly different compared with percentage of uptake in controls.