ERBB2 and neoplasm: Attending to the markers defining tumour subgroups, the right cluster (yellow bar) contained the hormone-receptor-negative tumours; according to the low expression of ESR, PGR, ERBB2 and luminal keratins (KRT8 and KRT19) and high expression of basal keratins (KRT5, KRT14, KRT17) this subgroup corresponds to the basal-like tumours.