HDAC9 and nasopharyngeal carcinoma: Based on theirresults, they hypothesized that histone deacetylation contributes to thepathogenesis of NPC and indeed confirmed this in NPC-derived fibroblasts: genesencoding histone deacetylases (HDACs) are upregulated in NPC-derived fibroblasts.Histone deacetylase (HDAC) plays a key role in gene regulation by removing acetylgroups from specific lysine residues on histones, which increases DNA condensationand thus thereby decreases gene expression.