SRSF1 and amyotrophic lateral sclerosis: In striking contrast, the presence of the hexanucleotide repeat expansion in C9ORF72-ALS patients triggers the nuclear export of C9ORF72 repeat transcripts retaining intron-1 (Fig. 8h) consistent with our previous data showing that the sequestration of SRSF1 on synthetic hexanucleotide repeat expansions promotes nuclear mRNA export through the interaction with NXF1 (Fig. 6).