MMP9 and neoplasm: In conclusion, we observed increasing recruitment of VEGFR1+CD133+ HPCs to the lung during tumor metastasis and found high expression of CXCL-16, IL-2Rα, IL-2Rγ, MMP-1, MMP-9, PDGFR-α, SDF-1α, TGF-β, PECAM-1, and VE-cadherin in highly metastatic MDA-MB-435s cells.