To detect HER2 expression in cell lines, we performed qPCR and Western blotting in two breast cancer cell lines (SK‐BR‐3, [HER2 (3+)] and MDA‐MB‐231 [HER2 (‐)]), five BCa cell lines (TCCSUP, RT4, 5637, UM‐UC‐3, and T24), and an immortalized human bladder urothelium cell line (SV‐HUC‐1). The gene discussed is ERBB2; the disease is breast cancer.