HDAC9 and gastric cancer: Histone methylation inhibitor DZNep or histone deacetylation (HDAC) inhibitor SAHA consistently increased the expression of miR-133b/a-3p in GC cell lines, and last but not least, decreased levels of H3 acetylation and increased levels of H3K27me3 were observed in the promoter region of miR-133b, all this indicating that both histone methylation and histone acetylation might be responsible for miR-133b/a-3p downregulation, but simultaneously discover showed DNA methylation inhibitor 5-Azacytidine't didn't increased the expression of miR-133b/a-3p in GC cell lines [30].