BMPs are proteins that act to induce the differentiation of mesenchymal-type cells into chondrocytes and osteoblasts before initiating bone formation. They promote the differentiation of cartilage-forming cells and bone-forming cells near sites of fractures but also at ectopic locations. Some of the proteins induce the synthesis of alkaline phosphatase and collagen in osteoblasts. Some BMPs act directly on osteoblasts and promote their maturation while at the same time suppressing myogenous differentiation. Other BMPs promote the conversion of typical fibroblasts into chondrocytes and are capable also of inducing the expression of an osteoblast phenotype in non-osteogenic cell types. Intracellular signaling following engagement of receptors for some BMP proteins has been shown to involve the action of SMAD proteins. BMP-2 wild type binds to its cellular receptors via two distinct binding epitopes. The large epitope 1 is responsible for the high-affinity binding to the BMPR-IA receptor, the smaller epitope 2 provides the low-affinity binding to the receptor BMPR-II. Recombinant Human Bone Morphogenetic Protein-2 is a homodimeric, non-glycosylated polypeptide chain containing two 115 amino acid subunits with a total molecular mass of 26kDa.