TP53 and head and neck squamous cell carcinoma: Since DIRAS3 and p53 are both tumor suppressor genes that are frequently mutated or inactivated in malignancies, including HNSCC [10, 19], we first re-expressed DIRAS3 and p53 in CAL-27 and SCC-25 cells using an adenoviral vector expressing DIRAS3 and Gendicine, a recombinant adenovirus p53 agent, respectively.