To further confirm that the downregulation of INPP4B in NPC was due to DNA methylation, we have treated the C666-1 cells with a demethylation agent (5-aza-2′deoxycytidine) or a histone deacetylase (HDAC) inhibitor (trichostatin A). The gene discussed is INPP4B; the disease is nasopharyngeal carcinoma.