GDNF and glioma: Glial cell derived neurotrophic factor was isolated from the rat glioma cell line containing a 134 amino acid residues with dimers proteins, the molecular weight is 33∼35 kD, it is widely expressed in the central nervous system, and the expression of after puberty and damage increased GDNF in the neurons to protect glial scar reconstruction axon regeneration and sprout and then play an important role in myelination.