GDNF and myeloid sarcoma: An array of neurotrophic factors (NFs) secreted by astrocytes and microglia is important for the maintenance of neurons and oligodendrocytes during normal homeostasis, and in CNS pathogenesis, demyelinating models, particularly in EAE and even in the MS tissue, these include brain-derived neurotrophic factor (BDNF), CNTF, NGF, glial-derived neurotrophic factor (GDNF), and fibroblast growth factor basic (FGF2) [9, 12–14].