Figure 6.

ERα supports strong E2-mediated cell proliferation; ERβ reduces the proliferative stimulation of ERα in ERα/ERβ cells, and ERβ by itself supports very little if any hormone-enhanced proliferation. (A) Cell proliferation: ERα, ERα/ERβ, and ERβ cells in six-well plates were treated with Veh (0.01% EtOH) or 10 nM E2 (day 0). Treatment was repeated at day 2. Cell number was monitored by MTS assay. Treatment groups were monitored in triplicate in two separate experiments. (B) FACS analysis: cell cycle stages were analyzed by flow cytometry using BD-FACS Canto. Cells were fixed in 70% ethanol, stained for 30 min with 20 μg/ml PI in Triton-X in the presence of DNAse-free RNAse A, and PI staining was measured. (C) Gene expression of four M-phase-related genes in cells treated with control vehicle or 10 nM E2 for 24 h. mRNA level in vehicle-treated ERα cells was set at 1.