Sclerostin, the protein product of the SOST gene, is a potent inhibitor of bone formation. Sclerostin protein is widely expressed at low levels with highest levels in bone, cartilage, kidney, liver, bone marrow and primary osteeoblasts differentiated for 21 days, and was originally identified as an important regulator of bone remodeling, homeostasis, and links bone resorption and bone apposition. Recent studies have revealed that Sclerostin protein inhibits the bone growth probably by binding to the extracellular domain of the Wnt coreceptors LRP5 and LRP6 and disrupting Wnt-induced Frizzled-LRP complex formation.