Histopathological and immunohistochemical examination of the tumor specimen obtained after radical mastectomy confirmed ductal invasive breast cancer with negative immunostaining for prolactin receptors (PLRr) but positive immunostaining for estrogen (ER) and progesterone receptors (PGR) and a ki-67 labeling index of 8%. The gene discussed is PGR; the disease is invasive breast carcinoma.