CGAS and head and neck squamous cell carcinoma: Finally, to elucidate a relationship between the presence of free cdsDNA after genotoxic challenges and the observed alterations in protein levels and activity status of the cGAS/STING/IFN-1 pathway shown in Figure 4, free cdsDNA was extracted and quantified 72 h after the same treatment conditions in HNSCC cells (Figure 5).