ERBB2 and breast carcinoma: Gene expression analyses in breast cancer have led to the definition of five molecular subtypes (luminal A, luminal B, HER2-enriched, basal-like and claudin-low) and the claudin-low subtype has been characterized as a subtype of aggressive triple-negative breast cancers displaying a high enrichment for EMT-markers (including ZEB1) and genes providing stem cell-like features34.