S100A8 and head and neck squamous cell carcinoma: Indeed, S100A8 and S100A9 mRNA levels in poorly or undifferentiated HNSCC were significantly lower p = 0.0004 and p < 0.0001, respectively) than well or moderately differentiated tumors, which were indistinguishable from normal samples based on analysis of microarray data GSE6791 from the GEO database (Figure 7).