Immunohistochemistry staining of tumor infiltrating lymphocytes in in-house HNSCC tumors. (A) Immunohistochemical staining of two additional pairs of head and neck squamous cell carcinoma (HNSCC) tumors (MAPK pathway-mutated versus WT), showing increases in the levels of intratumoral infiltrations of CD8+ T-cells, dendritic cells, and neutrophils. T25 (MAPK-mutated HNSCC tumor with bearing HRAS p.G12S and MAPK1 p.R135K) versus T75 (MAPK-WT) and T06 (MAPK-mutated HNSCC tumors with HRAS p.G13D mutation) versus T39 (MAPK-WT). Scale bars of 100 μm are shown. (B) The corresponding isotype control stainings of MAPK-mutated T40, T25, and T06 as well as MAPK-WT T69, T75, and T39 are shown. Scale bars of 100 μm are shown.