We examined SELENBP1 expression levels in a panel of breast cancer cell lines which included 4 ER+ (MCF7, BT474, ZR75B, and T47D) and 7 ER– cell lines (HCC1937, SKBR3, HCC70, MB453, MB468, MB231, HS578T). The gene discussed is ESR1; the disease is breast carcinoma.