UBQLN1 and Alzheimer disease: Accumulation of ubiquitin in senile plaques and neurofibrillary tangles [25-28], changes in proteasome subunit composition in AD [29] and an association of AD with polymorphic variants of UBQLN1, encoding for ubiquilin which is a ubiquitin-like protein [30], are some of the signs pointing towards a role of the UPS in AD.