E2F4 and head and neck squamous cell carcinoma: To uncover any role E2F4 has in HNSCC progression and its relationship with immune infiltration, we conducted the following research: First, we analyzed E2F4 expression in HNSCC and normal mucosal tissues using Gene Expression Omnibus (GEO) datasets in an Oncomine database, and validated this with The Cancer Genome Atlas (TCGA) database; we then analyzed the relationship of the E2F4 level with prognosis.