Some of the mechanisms by which AR inhibits breast cancer cell growth have been explained, for example through the down regulation of cyclin D1 [10], by increasing DAX 1 expression that causes an inhibition of aromatase content [30], by up-regulating ER-beta gene expression [31], by down-regulating CMYC and KRAS expression in response to let-7a increased expression [11], and more. The gene discussed is CYP19A1; the disease is breast carcinoma.