PTEN and Epstein-Barr virus infection: Until now, several studies reported that DNA methylation patterns were higher in EBV positive tumors compared to the EBV-negative ones and that EBV infection was clearly demonstrated to induce specific methylation epigenotypes that lead to silencing of multiple tumor suppressor genes such as BIM, p16INK4A, p14ARF, p73, E-cadherin and PTEN in EBV–associated nasopharyngeal and gastric cancers [17], [35], [36], [37], [38].