CXCL12 and neoplasm: Other tumor-derived chemotactic factors secreted by both malignant and stromal cells that attract peripheral monocytes to the site of tumors include CCL3/macrophage inflammatory protein-1α/MIP-1α, CCL4/macrophage inflammatory protein-1β/MIP-1β, CCL5/regulated on activation normal T cell expressed and secreted/RANTES, CCL7/MCP-3, CCL8/MCP-2, CXCL12, and the cytokines, macrophage colony stimulating factor (M-CSF), PGF, and VEGF (Figure 1) (Lewis and Pollard, 2006; Murdoch et al., 2008; Mukaida and Baba, 2012).