Several other cytokines, chemokines, and growth factors have been identified to play roles in MSC tumor-tropism, including IL-8, CXCL1, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor beta (TGF-β), platelet-derived growth factor (PDGF), hypoxia-inducible factor (HIF)-1α, placental growth factor (PGF), CXCL16, and colony stimulating factor (CSF)-1. This evidence concerns the gene PGF and neoplasm.