ESR1 and breast cancer: To corroborate these observations, we assessed the protein expression levels of surrogate markers of glycolytic activity and immune infiltration in 49 treatment-naïve, primary breast cancers, including 39 triple-negative breast cancers (TNBC; i.e., ER-negative, PR-negative and HER2-negative) and 10 ER-negative/HER2-positive breast cancers using IHC staining (Supp Table S6).