ESR1 and breast neoplasm: Remarkably, our observation (based on the data available at the TCGA database) that the mRNA level of HMGCR, a key enzyme involved in the cholesterol biosynthesis pathway [65], is overexpressed in the luminal subtype of breast tumours, is in line with our finding in ER+ breast cancer cells, that treatment with lovastatin (a known inhibitor of HMGCR) leads to a trend towards decreased lactate production levels, which is associated with glycolysis.