GDF-11, a member of the transforming growth factor ? (TGF?) superfamily, controls anterior/posterior patterning of the axial skeleton, regulates organogenesis by controlling expression of GDNF, contributes to the control of Hox gene expression and induces phosphorylation of Smad2. In addition, GDF-11 mediates signaling of Nodal during left-right patterning and development of head structures and inhibits generation of new neurons by neuronal progenitors in the olfactory epithelium.