Fig. 1.

Osteogenic lineage commitment of MSCs. The initial commitment of pluripotent MSC into osteogenic fate is induced by BMP, Wnt, Hedgehog and Nell-1 signaling pathways. While many BMP ligands promote osteogenesis of MSCs, BMP13 inhibits osteogenic differentiation of BM-MSCs by inhibiting calcium mineralization and alkaline phosphatase (ALP) activity. Notch plays an inhibitory role during initial commitment into osteogenic lineage, whereas it promotes the terminal differentiation of osteoblasts