CXCR4 and neoplasm: CXCL12 can promote the tumor process in four ways: it can promote neovascularization and provide oxygen supply to tumor cells45, it can directly promote tumor cell survival and proliferation in a paracrine manner46, it can cause tumor cell metastasis by interacting with its receptor (CXCR4), and finally, CXCR4 positive tumor cells may have stem cell characteristics and therefore a high potential for metastasis47,48.