Support for the role of another ATPase subunit, Rpt2, in PD came from the Drosophila model, in which Rpt2 knockdown in the CNS causes a decrease in proteasomal activity, increases the amount of insoluble ubiquitinated protein, and induces motor and non-motor phenotypes, which are believed to be Parkinson’s disease-like symptoms in the fly model [139]. Here, PSMC1 is linked to Parkinson disease.