SERPINE1 and head and neck squamous cell carcinoma: Intriguingly, the expression levels of the biomarker candidates, including ITGA5, PLAU, PLAUR, SERPINE1, and VEGFC, were positively correlated with the infiltration of CD4+ T cells, macrophages, neutrophils, and dendritic cells, but negatively correlated with the infiltration of B cells in HNSCC.