NOTCH1 and head and neck squamous cell carcinoma: In the last few decades, a number of molecular changes mainly involving oncogenes and tumor suppressor genes (e.g., NOTCH1, p16, and TP53) or genes regulating the cell cycle (e.g., EGFR and cyclin D1) have been identified in HNSCC, with NOTCH1 and TP53 being the most frequently found mutated genes [4].