The structure and ill vivo functions of the glial cell-derived neurotrophic
factor (GDNF) family ligands (GFLs) and their high-affinity receptors are
considered. These proteins play an important role in the development of the
nervous system, morphogenesis of the kidneys, and regulation of spermatoge
nesis. Tyrosine kinase Ret is a common receptor component for all GFLs. Its
role in multiple endocrine neoplasia type 2 (MEN2) is discussed.