As phase separation has been shown to promote stress granule assembly and drive pathological fibrillization (Molliex et al., 2015), LLPS of GR20 and PR20 raises the possibility that polyGR and polyPR might promote stress granule assembly in C9-ALS cells, though evidence of this effect is inconsistent; indeed, sometimes contradictory (Kwon et al., 2014; Wen et al., 2014; Tao et al., 2015; Lee et al., 2016). Here, C9 is linked to amyotrophic lateral sclerosis.