Dickkopf-related protein 3, also known as DKK3, is a member of the DKK protein family including Dkk-1, 2, 3 and -4. It is a secreted protein with two cysteine rich regions and is involved in embryonic development through its inhibition of the WNT signaling pathway. DKK3 is a 350 amino acid secreted glycoprotein that is composed of an N-terminal signal peptide and two conserved cysteine-rich domains, which are separated by a 12 amino acid linker region. The expression of this gene is decreased in a variety of cancer cell lines and it may function as a tumor suppressor gene. Recombinant human DKK3 protein, fused to His-tag at N-terminus, was expressed in E.coli.