ERBB2 and neoplasm: These numbers indicate that the genes associated with variations between luminal A and B samples are almost exclusively either under- or over-expressed relative to controls, in all luminal tumours, while they are diverging in basal-like and HER2-enriched subtypes when compared to luminal A. This observation additionally supports the hypothesis luminal A and B may share same cell mechanisms, resulting in similar characteristics with no clear boundary between them.