HTT and Huntington disease: Notably, control and HD model striatal neurons showed significantly increased proteasome activities [in control striatal neurons; chymotrypsin: 161±6% (p<0.05), PGPH-like: 143±7% (p<0.05), trypsin: 134±9% (p<0.05); in HD striatal neurons; chymotrypsin: 129±8% (p<0.05), PGPH-like: 123±7% (p<0.05), trypsin: 111±10% (p = 0.12)] compared to parental striatal cells (ST14A; without exogenous huntingtin transfection).