Based on genomic profiling, breast cancers are divided into several molecularly defined subtypes, including luminal A (ER/PR+, Her2-), luminal B (ER/PR/Her2+), Her2 (mostly Her2 amplified and ER-), normal-breast-like (the highest expression of the genes known to be expressed by adipose tissue and other nonepithelial cell types), and basal-like types (mostly ER-). This evidence concerns the gene ERBB2 and breast cancer.