Histone methylation. The methylation status of a histone is reversible. In contrast to histone acetylation, methylation of histones on different residues suppresses or enhances gene transcription. Methylation of H3K4 and H3K36 induces an open histone structure and hence promotes transcription. Methylation of H3K9 and H3K27 induces a compacted histone structure and hence suppresses gene transcription. Not altered. CC. Enhancing the Anticancer Efficacy of Immunotherapy through Combination with Histone Modification Inhibitors Wanyu Sun, Shuting Lv, Hong Li, Wei Cui and Lihui Wang