ERBB2 and breast cancer: •Low to absent gene expression of the ER-related genes, intermediate expression of HER2- related genes •High expression of proliferation, suppression of apoptosis, cell migration and/or invasion genes •High expression of (HMW) keratins 5, 6, 14, and 17, laminin, and FABP7 •BRCA1 mutations associated, none of the BRCA1 tumors showed evidence of ERBB2 amplification •Unique entity in breast cancer, more similarities with other cancer types •“stem/progenitor” cell phenotype •Multiple basal (TNBC) subtypes and mixed clinical response;. •TNBC often includes Claudin-low subtype.