VAPB and frontotemporal dementia: The previous studies showing that GSK3β activity regulates the PTPIP51–VAPB interaction, and thus mitochondria–ER associations, also linked the regulation of GSK3β activity to TDP-43 and FUS, two proteins associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD; Stoica et al., 2014, 2016).