AIM The stimulatory effect of resveratrol ( Resv, a natural phytoestrogen) has been reported on osteoblasts in vitro, whereas cyclosporine A (CsA, an immunosuppressant) was associated with bone loss in vivo. This project is intend to investigate the in vitro effect of Resv and CsA on osteoblastic differentiation in bone marrow-derived mesenchymal stem cells (BMSCs), and tries to identify whether the MAPK or ER/NO/cGMP pathway is involved in the stimulatory effect of Resv on BMSCs.