In tumors that stained positively for HER2 (HER2pos), cell surface HER2 expression in clusters of tumor cells was often co-localized with activated nuclear pSTAT3 (Table S1, Figure S1C), albeit with some heterogeneity of pSTAT3 staining, as described for other human breast tumor subtypes [17,22,23]. This evidence concerns the gene ERBB2 and neoplasm.