Therefore, in order to ascertain as to whether PD-L1 was modulated by glycosylation, HNSCC, FADU and Cal27 cells were added with PNGase F, the results of which revealed that the molecular weights of FADU and Cal27 cells exhibited a reduction from 45KD to 33KD following the addition of PNGase F (Fig. 2a), indicating that PD-L1 was modulated by glycosylation in FADU and Cal27 cells. This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.