Immunofluorescent microscopy detected a clear and homogeneous PD-L1 signal on the surface of cultured BICR6 cells, confirming and extending our observations made by immunoblotting, suggesting that PD-L1 is functional in HNSCC cells exposed to 5-FU + IFN-γ (Fig. 4B). This evidence concerns the gene IFNG and head and neck squamous cell carcinoma.