Glial cell line-derived neurotrophic factor and is the first member of the GDNF family of ligands (GFL) found. Glial cell line-derived neurotrophic factor has been shown to interact with GFRA2 and GDNF family receptor alpha 1. GDNF has regenerative properties for brain cells and showed potential as treatment for Parkinson's disease - monkeys with an induced form of Parkinson's disease showed less trembling when treated with the drug, and neuronal fibres grew in part of the human brain exposed to the drug. However progress to a treatment is hampered by the problem of delivering the drug to brain cells through the blood-brain barrier in human.
Guidepost cells in the neural tube of Drosophilia available for the binding of growing axons. These studies have defined guidepost cells as non-continuous landmarks located on future paths of growing axons by providing high-affinity substrates to bind to for navigation. Guidepost cells are typically immature glial cells and neuron cells, that have yet to grown an axon. They can either be labeled as short range cells or axon dependent cells. To qualify as a guidepost cell, neurons hypothesized to be influenced by a guidance cell are examined during development. To test the guidance cell in question, neural axon growth and migration is