On the basis of our previous finding that radiosensitivity in HNSCC cells is strongly related to their ability to undergo senescence after irradiation, specifically that HN31 mt p53 cells are radioresistant and have low levels of radiation-induced senescence, and our current findings that RITA decreased viability and increased senescence in HN31 cells, we investigated whether RITA could act as a radiosensitizer. This evidence concerns the gene TP53 and head and neck squamous cell carcinoma.