Background To explore the effect of human osteopontin (hOPN) on the proliferation, transmigration and expression of matrix metallproteinase-2 (MMP-2) and matrix metallproteinase-9 (MMP-9) in osteosarcoma (OS) cells in vitro.Methods The prokaryotic-expression vector of hOPN was produced. hOPN was then subcloned into E coli BL21 (DE3) cells and purified with ProBondTM Columns. The proliferation, cell cycle and the expression of cyclin A in OS cells were investigated by using MTT assay, flow cytometry and Western blot respectively. The transmigration of OS cells was checked by using transwell cell culture chamber. The micro-pore-filter-membrane system was used to study the chemiotaxis of hOPN to OS cells. The levels of total protein were examined according to Coomassie Brilliant Blue manuals. The expression of MMP-2 and MMP-9 were evaluated by detecting the volume of degradation of gelatin on SDS-PAGE gel.Results The prokaryotic-expression vector of hOPN and purified hOPN protein were achieved hOPN promote Background To explore the effect of human osteopontin (hOPN) on the proliferation, transmigration and expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase- 9 (MMP- 9) in osteosarcoma (OS) cells in vitro. Methods The prokaryotic -expression vector of hOPN was produced. hOPN was then subcloned into E. coli BL21 (DE3) cells and purified with ProBondTM Columns. The proliferation, cell cycle and the expression of cyclin A in OS cells were investigated by using MTT assay, flow cytometry and The transmigration of OS cells was checked by using transwell cell culture chamber. The micro-pore-filter-membrane system was used to study the chemiotaxis of hOPN to OS cells. The levels of total protein were examined according to Coomassie Brilliant Blue manuals. The expression of MMP-2 and MMP-9 were evaluated by detecting the volume of degradation of gelatin on SDS-PAGE gel. Results of the prokaryotic-expression vector of hOPN and purified hOPN protein were ach ieved hOPN promote