ESR1 and breast cancer: The repressing transcription mechanism of ERα in breast cancer is orchestrated either solely by DNMTs, or by a combination of DNMTs and HDACs, and corepressor complex elements (Sharma et al., 2006; Yang, 2001; Zhou et al., 2007; Bicaku et al., 2008; Yang, 2000; Sharma, 2005; Kawai et al., 2003).