2.1. Cell Lines

NPC cell lines (HONE1 and HONE1-EBV cells) and GC cell lines (AGS and AGS-EBV cell lines) were cultured in Roswell Park Memorial Institute 1640 Medium (Sigma, St. Louis, MO, USA). EBV-negative OSCC cell lines, SCC25 and HSC1 cell lines, (kindly provided by Dr. Tohru Kiyono, National Cancer Center (NCC), Chiba, Japan) and previously established EBV-positive OSCC cell lines, SCC25-EBV and HSC1-EBV cell lines [7], were maintained in Dulbecco’s Modified Eagle Medium/F12 (Sigma, St. Louis, MO, USA). All cell lines were supplemented with 10% fetal bovine serum (Gibco, Breda, The Netherlands) and penicillin-streptomycin solution. The cells were cultured at 37 °C in a 5% CO₂ incubator.