HIF1A and head and neck squamous cell carcinoma: HPV-positive HNSCC cells were demonstrated to have greater HIF-1α protein levels in both normoxic and hypoxic conditions [134], and given that it is well known that patients with HPV positive HNSCC have a better prognosis compared to HPV-negative disease, this suggesting that HIF-1α may play a role in enhanced sensitivity to radiotherapy.