Persephin (PSP) is a secreted protein belonging to the family of neurotrophic factors that includes GDNF, neurturin (NTN) and artemin, all distantly related to the TGF-beta superfamily. Neurotrophic factors play in a role in development and maintenance of the nervous system. Persephin is reported to promote both the survival and growth of central dopaminergic and motor neurons, and kidney development, but does not support the peripheral nervous system. It is expressed at very low levels in many tissues. Persephin does not seem to signal through the same receptor complex as other family members GDNF and neurturin, but uses subunit GFR alpha-4 along with the receptor tyrosine kinase RET.