Bone morphogenetic protein（BMP）, one of multifunctional secreted signaling molecules, is a member of the transforming growth factor-β superfamily. BMP regulates a wide spectrum of cellular functions such as proliferation, differentiation, migration and apoptosis, and also plays central roles in morphogenesis of various organs, embryonic development as well as reparation of injured tissues. Smad（sma-mad） protein is intracellular signaling
transduction and regulatory molecules of BMP. Signal transduction studies have revealed that Smad can transduce the BMP signal from the cellmembrane to the nucleus, forming the BMP/Smad singaling pathway. Recently, researches
have show that BMP/Smad singaling pathway regulates bone formation in distraction osteogenesis（DO）. Indepth understanding of osteoblast BMP/Smad signaling pathway to stimulate the mechanical response mechanisms
and the role of molecular biology DO mechanism for the application of exogenous BMP and provide a theoretical basis for gene therapy.
