CA9 and head and neck squamous cell carcinoma: In the search for potential biomarkers in HNSCC, we examined mRNA expression of five highly upregulated (CA9, CASP14, LOX, GLUT3, SERPINE1) and four highly downregulated (AREG, EREG, CCNB1 and KIF14) hypoxia-responsive genes in 32 HNSCC tumors and six adjacent normal oral tissue.