ESR1 and breast cancer: Among others, we noticed a reduction of ERα co-immunoprecipitation with epigenetic modulator proteins such as the Bromodomain Adjacent To Zinc Finger Domain 1B (BAZ1B), the scaffold protein menin 1 (MEN1) and the Enhancer Of Zeste 2 Polycomb Repressive Complex 2 Subunit (EZH2), previously identified to be involved with ERα in controlling key BC hallmarks (Fig. 1A) [32, 33].