Human OSCC cell lines (HSC‐2, HSC‐3, and HSC‐4) were obtained from the Japanese Collection of Research Bioresource Cell Bank. HSC‐3pp65 cells transfected with cytomegalovirus (CMV)pp65 antigen and Td‐Tomato in HSC‐3 cells were prepared as previously described.25 (link) The cells were maintained in DMEM (Gibco) supplemented with 10% fetal bovine serum (FBS; HyClone Laboratories, Inc South Logan) and 1% penicillin‐streptomycin (Gibco, Grand Island, NY, USA) in 75 mL flasks at 37°C in 5% CO2 humidified air. Only HSC3pp65 cells were cultured in a culture medium supplemented with 250 μg/mL G418.