C9 and amyotrophic lateral sclerosis: Colocalization and G4C2-pull down studies in C9-ALS brain tissues as well as iPSC-derived neurons have identified multiple RNA-binding proteins (RBPs) that interact with the G4C2 repeat RNA, including hnRNP-family proteins (hnRNPA1, A2/B1, A3, K, H1, H3), ALYREF, ADARB2, RanGAP1 and MATR3 [7, 24, 25].