CXCL12 and neoplasm: It has been well accepted that TAMs are generally recruited from blood monocytes by diverse chemokines such as CCL2 (MCP-1), CCL5, CCL7, interleukin 8 (IL-8, CXCL8) and CXCL12, followed by migration to diverse areas of the tumor microenvironment and differentiation according to surrounding cellular or environmental stimuli [13].