The ubiquitin ligase 3-hydroxy-3-methylglutaryl-coenzyme A reductase degradation 1 (HRD1) and its stabilizing molecule, the suppressor/enhancer lin-12-like (SEL1L), can suppress the ER stress via the ubiquitin-proteasome system, and that HRD1 can also suppress cell death in familial and nonfamilial PD models. This evidence concerns the gene SEL1L and Parkinson disease.