S100A9 and head and neck squamous cell carcinoma: Expression of S100A8 and S100A9 was downregulated in HNSCC (S100A8, 2.9-fold, FDR = 1.1×10−16; S100A9, 2.6-fold, FDR = 6.8×10−14), but was not correlated with tumor size (T stage) (Figure 2A).