Figure 2.

Hormone-independent effects of ER on cell cycle phase distribution in hormone-sensitive MCF-7 cells. Hormone-depleted MCF-7 cells were transfected with either ER siRNA or control siRNA and maintained in hormone-depleted conditioned media without further replenishment of the media. Twenty-four hours after transfection, cells were treated with vehicle (No ligand), E₂ (1 nM) or OH-Tam (100 nM); the treatments were repeated every 48 hours without changing the media. (A) On the indicated days, the cells as treated above were harvested for flow cytometry analysis to determine their cell cycle phase distribution. (B) On Day 4 of the above treatment, cells were harvested to measure the proportion of apoptotic cells by Annexin V staining. P-values for the differences noted in the text were ≤0.001.