Uroporphyrinogen decarboxylase (UROD) downregulation induced caspase-mediated apoptosis and cell cycle arrest in head and neck cancer cells and radiosensitized several different models of human cancer, increasing tumor cell sensitivity to chemotherapeutic agents, including 5-fluorouracil, cisplatin, and paclitaxel [56]. The gene discussed is UROD; the disease is neoplasm.