Previous studies have shown that ERα activation is associated with DNA methylation and histone modifications; we therefore assessed epigenetic-modulating enzymatic activity of the DNMTs (Fig. 3A), HDACs (Fig. 3B), HATs (Fig. 3B) and DNMTs as well as HDACs expression (Fig. 3C) in ERα-negative MDA-MB-231 breast cancer cells, using GTPs and SFN treatments. Here, ESR1 is linked to breast cancer.