C9orf72 and amyotrophic lateral sclerosis: Given the insolubility of a broad range of related RBPs that we observed in the brain and spinal cord of patients with ALS/FTD carrying the C9orf72 expansion mutation and in sporadic ALS27, we looked in the P517L/WT and P517L/P517L animals to see if FUS insolubility was associated with a similar increase in insoluble RBPs.