However, for ALS-causing PFN1 and SOD1 mutants with the co-existence of both folded and unfolded states, which are separated by relatively large energy barriers and exchanging on the ms time scale, the capacity of phosphate to induce their folding is too weak and, consequently, diphosphate, triphosphate, or ATP is needed to induce their folding [26]. Here, PFN1 is linked to amyotrophic lateral sclerosis.