ESR1 and breast neoplasm: We examined four mRNA profile datasets of human tumors: the dataset of ERα+ breast tumor profiles used above (Figure 2); a dataset of 69 ERα- breast tumors [14]; a compendium of 174 tumors from 11 different histological types (including breast; the 'Novartis' dataset) [24]; and a second compendium of 138 tumors from 13 different types (the 'MIT' dataset) [25].