Objective:To investigate the status of BMP/Smads signaling pathway on the bone of lupus mice(MRL/lpr). Methods:The femurs of the mice were isolated,and the bone structure was detected by hematoxylin-eosn(HE)staining. The protein expression levels of bone morphogenetic protein-2 (BMP-2)were measured by immunohistochemistry. Bone marrow mesenchymal stem cells(BMMSCs)were isolated by the density gradient centrifugation and the adherence screening methods. After BMMSCs growing on coverslips,the protein of BMP-2 and PSmad1/5/8 was valued by immumofluorescence method. The mRNA expressions of ALP,Runx2 of BMMSCs were measured by Real-time PCR,and the Alkaline phosphatase (ALP)staining was performed for measuring the early osteogenic differentiation induced by BMP-2. Results:Compared with the controlled mice,the cortex of MRL/lpr mice were reduced (P < 0.01). There was no difference in the BMP-2 expression on the bone of the two groups by immunohistochemistry detection(P > 0.05). The expressions of BMP-2 and PSmad1/5/8 in BMMSCs of lupus mice were lower than those of the control group(P < 0.05). After 7 days of BMP-2 stimulation,ALP activities of BMMSCs from lupus mice were decreased compared with the control group. The mRNA levels of ALP in lupus mice were lower than that of C3He/HeJ mice (P < 0.01),while there were no differences in the Runx2 mRNA levels between the two groups after BMP-2 stimulation(P > 0.05). Conclusion:BMP/Smads signaling was inhibited in the bone of lupus mouse.