Centroids for the established subtypes (basal-like, claudin-low, ERBB2+, luminal A, luminal B and normal-like) and the mApo subtype were computed based on reference samples from Prat [8], and Farmer [5] respectively, whereas the centroid for the luminal-like subtype was calculated based on the 397 samples defined as luminal-like in our tumor collection. The gene discussed is ERBB2; the disease is neoplasm.