Figure 3A shows that breast cancer patient biopsies, breast cell lines, and xenograft models primarily cluster together by breast cancer subtype [LumA, LumB, normal, human epidermal growth factor receptor 2 (HER2)–enriched, or basal], with only a few PTX basal subtype models clustering elsewhere (see also fig. The gene discussed is ERBB2; the disease is breast carcinoma.