Placental aromatase promoter constructs and the effect of TGF-β1 on promoter activities. A) Various lengths (-2538 to -117) of the 5' flanking region of the placental specific exon 1 were cloned into a luciferase reporter construct pGL3 basic. Smad binding elements (SBE) are shown at the red box region. JEG-3 cells cultured in 6-well plates were transfected with these luciferase constructs (1 μg) and then treated with or without TGF-β1 (1 ng/ml) for 6 h. B) Cells were transfected with Arom -714 construct and then treated with TGF-β1 (1 ng/ml) for the duration as indicated. C) Cells were transfected with Arom -714 - and then treated with different concentrations of TGF-β1 for 6 h. In these experiments, a β-galactosidase expression vector (0.5 μg) was co-transfected into cells for normalizing transfection efficiency. Relative luciferase activity was calculated as the ratio of luciferase/β-gal. Data are mean ± SEM of three replicates from one experiment. The experiment has been repeated twice with similar results. *, P < 0.05 verse empty vector control.