GDF-15 belongs to the TGF-β cytokine family whose members play an important role during prenatal development and postnatal growth, remodeling and maintenance of a variety of tissues and organs. GDF-15 is expressed predominantly in placenta and to a much lesser extent in various other tissues. The presence of GDF-15 in amniotic fluid and its elevated levels in the sera of pregnant women suggest a role for GDF-15 in gestation and embryonic development. GDF-15 generally exerts tumor suppressive activities and is one of the predominant factors produced and secreted in response to activation of the p53 pathway. Interestingly, the serum level of GDF-15 is positively correlated with neoplastic progression of several tumor types, including certain colorectal, pancreatic, and prostate cancers. Human GDF-15/MIC-1 is a disulfide linked homodimeric protein consisting of two 114 amino-acid polypeptide chains.