ERBB2 and breast carcinoma: [56], who developed the revolutionary PAM50 gene expression assay categorising breast cancer into intrinsic molecular subtypes using an assay that measures the expression levels of 50 genes (the PAM50) to classify breast cancers into one of five subtypes: Luminal A, Luminal B, HER2‐enriched, Basal‐like, and Normal‐like.