As PAI-1 is a prognostic marker for poor outcome and is involved in tumour progression, a better understanding of the factors (e.g., hypoxia and irradiation) responsible for PAI-1 up-regulation in SCCHN is vital for treatment planning of patients with these especially hypoxic and radioresistant tumours. The gene discussed is SERPINE1; the disease is head and neck squamous cell carcinoma.