VAPB and proteostasis deficiencies: Like other proteins linked to neurodegenerative diseases, mutant VAPB, transiently expressed in a variety of cultured cells, forms intracellular inclusions; for this reason, mutant VAPB-associated ALS has long been regarded as a protein misfolding disorder [116,147,150,151,152], implying that the efficiency of the removal of the mutant protein from the cell may be an important factor in its toxicity.