Importantly, neuron-specific expression of Usp14 also restored cellular monomeric ubiquitin to wild type levels, confirming the role of this proteasome-associated DUB in governing ubiquitin homeostasis and supporting a presynaptic role for USP14 in the ataxia phenotype of the axJ mice [60, 62]. This evidence concerns the gene USP14 and cerebellar ataxia.