CXCR1 and cancer: Singh et al. [58] found that the proliferation and migration ability of endothelial cells would be significantly inhibited when the expression of CXCR1/2 in endothelial cells was knocked out, suggesting that CXCL8, the ligand of CXCR1/2, may contribute to angiogenesis and provide adequate nourishment to the cancer cells, resulting in tumor progression.