To explore in detail the potential of RNA-seq in reconstructing a BC classification system originally developed with a different technology, we considered the so-called “intrinsic molecular subtypes” (Luminal A, Luminal B, Normal-like, Her2-Enriched and Basal), which have become part of the common knowledge on the disease and are recognized as prognostically and therapeutically relevant7. Here, ERBB2 is linked to breast cancer.