CK19 expression in cell lines from the Luminal subtypes of breast cancer (MCF7 and T47D) and the HER2 positive subtypes of breast cancer (SKBR3) was detected, while no expression of this protein was detected in cell lines from the other subtypes same as Normal-like/claudin-low (MDA-MB-231). The gene discussed is ERBB2; the disease is breast carcinoma.