Other epigenetic events, such as histone deacetylation, are also involved in the complex mechanisms that regulate the transcription of the ER-α promoter.20, 21 Notably, DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, which are candidates for new cancer therapeutics, can synergistically reactivate ER-α expression in ER-α-negative breast cancer cells and restore responsiveness to antiestrogen therapy.22 The gene discussed is ESR1; the disease is cancer.