RASSF1 and nasopharyngeal carcinoma: Recent findings suggest that epigenetic inactivation of multiple tumor suppressor genes plays an important role in the tumourigenesis of NPC, such as aberrant methylation of the 5-CpG island of Ras association domain family 1A (RASSF1A), RARβ2, death-associated protein kinase (DAP-kinase), p16 (CDKN2A), p15 (CDKN2B), p14 (ARF) and O6-methylguanine DNA methyltransferase (MGMT), DLC1, TSLC1, TIG1 in NPC [27-33].