The concentration-response curves to E
(a), genistein (b), and ferutinin (c). The curves were constructed by exposing HELN-ERα (ERα), HELN-ERβ (ERβ), HELN-ΔA/BERα (ΔAB-ERα), and HELN-ΔA/BERβ (ΔAB-ERβ) cells to increasing concentrations of E2, genistein, and ferutinin for 16 hours at 37°C in a 5% CO2 humidified atmosphere. The results are expressed as a percentage of maximum luciferase activity (100%), which was determined when the cells were exposed to 10-8M E2. Each value at each concentration in the response curves is the mean ± standard deviation from three separate experiments.