PFN1 and amyotrophic lateral sclerosis: Such internal voids are structurally more disruptive than peripheral, solvent-exposed cavities, which explains the particularly high instability and aggregation propensity of PFN1 C71G among the biochemically characterized ALS-PFN1 mutants (Eriksson et al., 1992b, a; Del Poggetto et al., 2015a; Xue et al., 2019).