HDAC4 and nasopharyngeal carcinoma: To investigate the impact of HDAC4 downregulation on the proliferation and the invasive and migratory abilities of NPC cells, we stably expressed two shRNAs targeting different HDAC4 coding regions (#1 and #2) or a scrambled nontargeting shRNA (Scr) in the 5-8F and S18 cell lines, which have a high basal expression of HDAC4, and examined the protein levels of HDAC4 by western blotting (Fig. 3A).