Our preclinical result revealed that curcumin reduced the cell viability of different breast cancer cell lines, including MCF-7 (ER-positive, HER-2-negative), MDA-MB-231 (ER-negative, HER-2-negative), HER-2-overexpressed BT-474 (ER-positive, HER-2-positive), and herceptin-resistant SK-BR-3-hr (ER-negative, HER-2-positive) cells. The gene discussed is ESR1; the disease is breast carcinoma.