FUS and amyotrophic lateral sclerosis: To explore whether FUS regulates hnRNP K and subsequent MP20, we investigated the effects of ALS-associated P525L FUS mutant, which is a mutation in the nuclear localization signal of FUS, disrupting its nuclear localization and inducing cytoplasmic aggregation (Lenzi et al., 2015; Liu et al., 2015) (Fig. 9 B).