XCL2 and cancer: Chemokine-related receptor and ligand genes remain popular worldwide, and the CXCL12/CXCR4/CXCR7 signaling pathway is the most widely studied, playing an important role in tumor progression, angiogenesis, cell metastasis, and survival, the effects of XCL2, an important member of the chemokine family, on human cancer have rarely been systematically explored and studied.