CXCR4 and head and neck squamous cell carcinoma: Both IFNs have anti-angiogenic activities [55,56] and significantly repress CXCR4 gene expression that can lower the vascularity surrounded NMSC and impact in SDF-1-induced cell migration and proliferation of CXCR4-positive cells as have been demonstrated in head and neck squamous cell carcinomas for IFN-γ [57].