SOD1 and amyotrophic lateral sclerosis: With application to amyotrophic lateral sclerosis (ALS), Dodge, et al. showed that expression of adeno-associated virus serotype 4 (AAV4)-mediated expression of insulin-like growth factor-1 (IGF-1) or vascular endothelial growth factor (VEGF-165) found in the ventricular system, including the ependymal cell layer and spinal cord central canal, lead to trophic factor delivery throughout the central nervous system and increased survival of cytosolic copper–zinc superoxide dismutase (SOD1) in transgenic mice [46].