SOD1 and amyotrophic lateral sclerosis: This idea has gained support from a study focusing on amyotrophic lateral sclerosis (ALS), which showed that focal transplantation of glial-restricted precursors (GRPs) exerted a neuroprotective effect along with functional improvement (prolonged survival and attenuated motor neuron loss, as well as slowed declines in forelimb motor) in transgenic rats expressing human mutant superoxide dismutase-1 (SODG93A).