(A) The morphological changes after 8 weeks treatment with different combinations. MCF-7:5C cells were long-term treated with vehicle (0.1% EtOH), PP2 (5×10−6mol/L), E2 (10−9 mol/L), and E2 (10−9mol/L) plus PP2 (5×10−6mol/L) in T25 flasks, respectively. Cells were photographed under bright field illumination at (×20) magnification (Zeiss). (B) Cell-cycle changes after different treatments. Cells treated in different combinations were harvested and gradually fixed with 75% EtOH on ice. After staining with propidium iodide (PI), cells were analyzed through flow cytometry. All the data shown were representative of at least three separate experiments with similar results.