Thrombin promoted MSCs to express and secrete FN. A-C: MSCs were serum-deprived for 24 to 48 h and then maintained in the presence or absence (as control, CTR) of thrombin (4 U/ml, TH) for 24 h. FN mRNA expression by MSCs was analyzed by semi-quantitative quantitative RT-PCR (A) and real-time quantitative PCR by comparing the ΔCt method. The FN expression level was presented as fold change (fold change = 2-ΔΔCt) compared with control group (B, **P <0.01). C: Cellular immunofluorescence was performed to assess FN expression in BMSCs (Magnification: 100×). D: MSCs were treated with thrombin at a dose of 4 U/ml for the indicated times (left) or thrombin at the indicated concentrations for 24 h before the contents of FN in the supernatants were detected by ELISA. The data are representative of those from MSCs from four individual donors. BMSCs, Human bone marrow mesenchymal stem cells; FN, Fibronectin; MSCs, Mesenchymal stem cells.