Figure 1

ER expression of mammary carcinoma cells. A. Western blots of ERα in mammary carcinoma BJMC3879luc2 cells showed bands between 50 and 64 kDa, but the MCF-7 human breast cancer cell line showed a ~66 kDa form. ERβ was not detected by western blots. B. In immunofluorescence staining, this smaller form showed cytoplasmic localization (green). Nuclear stain was conducted with PI (red). Bar = 10 μm. C. Cell proliferation was significantly increased by the addition of 10 nM E2 (**P < 0.01), but cell proliferation was not changed in any other concentration of E2, with the exception of the highest concentration of 100 μM, which is toxic. In the case of BJMC3879luc2-implanted tumors in mice, the tumor volume was slightly bigger in the female mice as compared to the male mice (D), and ERα mRNA levels were significantly higher in the implanted tumors in females than those in males (*P < 0.05) (E).