The four prototypical tumor subtype centroids (Basal-Like, HER2-Enriched, Luminal A, and Luminal B) were defined by identifying statistically significant (P < 0.001) clusters from hierarchical clustering of the PAM50 genes in 514 samples from the BC no AST, UNC, and WashU cohorts and 24 reduction mammoplasty samples (Fig. 2). This evidence concerns the gene ERBB2 and breast cancer.