CCL2 and neoplasm: Menon et al. found that MSC exposure to tumor cell conditioned media up-regulates mRNA levels of 104 genes, including genes for stromal cell-derived factor 1 (SDF-1/CXCL12), monocyte chemotactic protein 1 (MCP-1/CCL2), and growth-regulated protein β (Gro-β/CXCL2), which are all potent chemokines that act in an autocrine fashion to further stimulate MSC migration [35].