CXCL12 and neoplasm: Abnormal tumor vessels further exacerbate hypoxia, which in turn increases the secretion of chemotactic cytokines - including CCL2, CCL22, CCL28, CXCL8, and CXCL12 - that recruit immunosuppressive MDSCs, M2-like TAMs, and Tregs into the tumor[130,131].