Interesting implications on the COX-1 role derive also from in vitro investigations in head and neck squamous cell carcinoma (HNSCC) cell lines, in which the effects of pharmacologic inhibitors of cyclooxygenases were compared to those of small-interfering RNA as far as cell-growth, vascular endothelial growth factor (VEGF) production, and intracellular signaling are concerned [56,57]. Here, PTGS1 is linked to head and neck squamous cell carcinoma.