CXCR6 and head and neck squamous cell carcinoma: Consistent with the results mentioned above, CXCR1 to CXCR6 were highly expressed in HNSCC tissues, which showed a negative correlation with tumor purity (Fig. 7) and suggested that there was a significant correlation between TIICs and CXCR members, CXCR3-6 in particular.