MMP1 and neoplasm: Numerous signaling molecules, including stromal derived factor-1 (SDF-1/CXCL12), transforming growth factor-β (TGF-β), interleukin-8 (IL-8), matrix metalloproteinase-1 (MMP-1), and monocyte chemoattractant protein 1 (MCP-1/CCL2) were shown to be involved in MSC recruitment to the primary tumor site [46–49].