However, in postmenopausal women, although the ovarian function deteriorates, an increase in adipose-derived leptin will not only induce the production of estrogen mediated by aromatase in MCF7 breast cancer cells (23), but also activate the signal transduction of estrogen receptor (ER) (23, 24), which will increase the level of estrogen. This evidence concerns the gene CYP19A1 and breast cancer.