For instance, circulating hypoxia activated hypoxia-inducible factor 1(HIF-1) and NF-κB in tumor cells, which resulted in increased production of VEGF-A, CCL2/MCP-1, CXCL1, CXCL8/IL-8 and prostaglandin E2(PGE2). Here, CCL2 is linked to neoplasm.