Our extensive model of a typical post-menopausal breast cancer patient includes inducing a syngeneic, orthotopic, ER+ mammary tumor with subsequent surgical removal by radical mastectomy, then a repeated chemotherapy regimen, followed by long-term aromatase inhibitor treatment in an ovariectomized (modeling post-menopause) female mouse. The gene discussed is CYP19A1; the disease is breast carcinoma.