CXCR2 and head and neck squamous cell carcinoma: Having shown that the induction of an early senescence response paralleled by the upregulation of acute SASP cytokines and particularly ligands of the CXCR2 receptor upon radiotherapy is a therapeutically targetable determinant of radioresistance in preclinical models of HNSCC, we next examined the clinical relevance of CXCR2 and its ligands in HNSCC patients.