Objective:　To　investigate　the　modulation　of　pilose　antler　extract　(PAE)　on　rat　osteogenic　cells　UMR-106　in　vitro.　Method:　Component　P2　of　PAE　was　isolated　by　Sephacryl　S-200HR　gel　filtration　chromatography.　The　proliferative　effects　of　P2　and　other　components　isolated　by　Sephacryl　S-200HR　on　UMR-106　cells　were　investigated　by　MTT　assay.　Result:　The　P2　could　significantly　increase　the　proliferation　rate　of　osteogenic　cells.　When　the　protein　concentration　of　P2　was　between　0.972　mg·L-1　and　97.2　mg·L-1,　it　could　inhibit　the　proliferation　of　UMR-106　cells.　But　while　the　concentration　was　equal　to　or　greater　than　97.2　mg·L-1,　the　P2　could　increase　the　proliferation　rate　of　cells,　especially　477.92%　at　9.72　g·L-1,　which　was　approximated　to　499.62%　of　PAE.　The　molecular　weight　of　the　P2　was　about　59kDa　determined　by　SDS-PAGE.　On　the　other　hand,　inhibition　was　also　observed　in　the　sample　of　the　P3,　P4　and　P5.　Conclusion:　Those　regulative　factors　in　PAE　which　have　different　molecular　weight　can　affect　the　proliferation　of　UMR-106　cells　two-wayly.　And　this　adjustment　also　relies　on　the　dose　of　those　factors.　This　finding　may　help　us　to　understand　the　possible　mechanism　of　Chinese　traditional　medicine　from　animal　materials.