The BT474 cell line is a clinically relevant model to investigate the effects of AR (and other candidate molecules that may influence/trigger cancer progression) in BCa, since it was derived from a ductal carcinoma, luminal B type, representative for Stage II cancer of a post-menopausal woman and expresses AR, ER, PR, and HER2 receptor [18–21]. The gene discussed is ESR1; the disease is cancer.