SOSTDC1 is a member of the sclerostin family and an N-glycosylated, secreted protein with a C-terminal cystine knot-like domain. This protein functions as a bone morphogenetic protein (BMP) antagonist. Specifically, it directly associates with BMPs, prohibiting them from binding their receptors, thereby regulating BMP signaling during cellular proliferation, differentiation, and programmed cell death. Recombinant human SOSTDC1 protein, fused to His-tag at N-terminus, was expressed in E.coli.