Abstract Serine/threonine receptors transduce signals for the TGF-β family, several members of which, such as decapentaplegic and bone morphogenetic proteins, are involved in early patterning of the embryo. The gene encoding the anti-Müllerian hormone (AMH) receptor has recently been cloned; gene targeting produces the same effects as targeting of the AMH gene itself. Another divergent member of the TGF-β family. GDNF, signals through Ret, a tyrosine kinase receptor; binding to Ret requires the cooperation of GDNFR-α. The signal transduction pathway of serine/threonine receptors is now being intensively studied; the immunophilin FKBP-12 and MAD proteins are known to be involved.