By inhibiting the Wnt/β-catenin pathway, IGF-1 reduces the osteogenic differentiation of BMSCs. BMSCs were transfected with empty vector or the siRNA-Wnt3a gene. Then, the cells were treated with IGF-1 (80 ng/ml). (A) Alkaline phosphatase staining of BMSCs for 1 week. (B) Alizarin Red staining of BMSCs for 3 weeks. (C) β-catenin, RUNX2 and OPN protein expression was determined by western blotting for 1 week. (D) The relative mRNA expression of β-catenin, RUNX2, and OPN was evaluated by quantitative polymerase chain reaction for 1 week. (E) Immunofluorescence was used to detect the expression of β-catenin, RUNX2 and OPN in BMSCs for 1 week. ***P<0.001 vs. IGF-1 + EV. IGF, insulin growth factor; BMSCs, bone marrow mesenchymal stem cells; RUNX2, runt-related transcription factor 2; OPN, osteopontin; si, small interfering; EV, empty vector.