To examine biological characteristics of a panel of breast cancer cell lines, immunocytochemical analyses for ER-α, PgR, HER2, HER1, cytokeratin 5/6, vimentin, BRCA1, p53, c-Src, p-Src (Y416) and p-Src (Y527) were performed (Additional file 1). The gene discussed is ESR1; the disease is breast carcinoma.