Glial cell line-derived neurotrophic factor (GDNF) was initially discovered as a neurotrophic factor that enhances survival of midbrain dopaminergic neurons. Findings in 1994 and 1995 extended the spectrum of biological activities of GDNF to different populations of neurons (motor and sensory). Recent findings revealed that GDNF, Neurturin (NTN), Persephin (PSP), and Artemin (ARTN) are members of the GDNF protein family and are structurally related to transforming growth factor protein family. They are survival factors for peripheral and central neurons, for oligodendrocytes and can promote morphogenesis of kidney in vitro.