CCR2 and neoplasm: MSC-derived CCL2 is an important chemokine receptor-ligand that mediates the recruitment of CCR2+ neutrophils into the tumor stroma.128 After initial recruitment the interaction between CCR2+ neutrophils and tumor cells leads to a significant increase in metastasis-related gene expression such as CXCR4, CXCR7, matrix metalloproteinase (MMP)-13, MMP-12, IL-6, and TGF-β in tumor cells.128,129