That agreed with mounting studies which demonstrated the ability of HDACIs, such as vorinostat, to reactivate ERα expression at both transcriptional and protein levels in ER-negative BC cell lines like MDA-MB-231 and in different aggressive subtypes of TNBC through an epigenetic mechanism, and they sensitized cells to the anti-estrogen drug tamoxifen [12, 27]. Here, ESR1 is linked to breast cancer.