One of the first histone lysine methyltransferase inhibitors (HKMTi), specific against G9a (EHMT2), was BIX-01294 (Kubicek et al., 2007), which has been shown to inhibit cell proliferation in BC cell lines and induce apoptosis in neuroblastoma cells (Cui et al., 2015). This evidence concerns the gene EHMT2 and breast cancer.