Exendin-4, a long-acting analog of GLP-1, was shown to have neurotrophic and neuroprotective properties, similar to other neurotrophic factors, in cultured PC12 cells subjected to excitotoxic stress (Perry et al., 2002a,b), suggesting that stimulation of GLP-1 receptors may be therapeutically beneficial in neurodegenerative disorders such as PD. The gene discussed is GCG; the disease is Parkinson disease.