Western blot analysis showed that major components involving in Cytochrome c mediated apoptotic pathways including Cytochrome c, Apaf-1, Caspase 9 and Caspase 3/7 were down-regulated in FaDu cells (Figure 3C) and SAS cells (Supplementary Figure S5A) cultivated in high-glucose environment suggesting long-term hyperglycemia protected HNSCC cells from Cytochrome c mediated cytotoxicity. This evidence concerns the gene CASP9 and head and neck squamous cell carcinoma.