Figure 7. Molecular mechanism and signaling pathways underlying BMP9 enhanced osteogenesis and angiogenesis in cocultured hAMSCs with HUVECs. ELISA was adopted to detect the effect of BMP9 that regulates protein expression of VEGF in cocultured hAMSCs and HUVECs (A); Western blot and quantification analysis were used to determine the expression of p-Smad1/5/8, Smad1/5/8, p-PI3K, PI3K, p-AKT, AKT, and mTOR in each group as shown at 5 d after transfection. The results suggested that BMP9 enhanced osteogenesis and angiogenesis of cocultured hAMSCs and HUVECs by activating the BMP/Smad and PI3K/AKT/m-TOR signaling pathways through upregulating the level of phosphorylation of Smad1/5/8 and of PI3K, AKT, and protein expression of m-TOR (B–F) (*P < 0.05).