Lysosomal storage disorders and lysosomal cysteine protease inhibitor E64 treatment were previously shown to down-regulate UCHL1[51], however, such is not the case in Ctsd-/- brains in our study, indicating a distinct mechanism of CD deficiency-induced proteasome dysfunction. The gene discussed is UCHL1; the disease is hyperinsulinemic hypoglycemia, familial, 4.