ERBB2 and neoplasm: In 2009, Parker et al. (25) introduced a gene expression-based test named PAM50, which identifies the intrinsic molecular subtypes in four well-established transcriptional subtypes, through the expression of 50 genes in formalin-fixed paraffin embedded (FFPE) tumor tissues: luminal A, luminal B, basal-like, and HER2-enriched (25, 28, 31).