Objective To investigate the effects of P17-BMP2 peptide on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs).Methods BMSCs derived from 4-week-old Wistar rats were isolated and expanded.Four groups were set in this study: Group A,which were cultured in regular medium(DMEM with 10% fetal calf serum);Group B,which were cultured in the regular medium with dexamethasone 107 mol/L,Vitamin C 10 mg/L and beta-glycerophosphate 10 mmol/L(induction medium);Group C,which were cultured in induction medium with P17-BMP2 10 μg/mL;and Group D,which were cultured in regular medium with P17-BMP2 10 μg/mL.Cell proliferation were measured at 1、3、5、7 days after culture by CCK-8 kit.Alkaline phosphatase(AKP) staining were performed 7 days after culture.The expressions of osteocalcin(OCN),osteopontin(OPN),runt-related transcription factor 2(Runx2) were evaluated by Q-PCR.Results Compared with group A,the proliferation of BMSCs were not promoted in group D,but promoted in group B and highly enhanced in group C.The alkaline phosphatase staining were all positive in each group,but the dyeing intensity were different: group C > group B > group D > group A.Compared with group A,the expressions of OCN,OPN and Runx2 were