In PD, proteins with abnormal S-nitrosylation include Parkin (a ubiquitin ligase and a familial PD gene), protein disulfide isomerase (PDI, whose impairment causes ER stress), Prx2 (a protein that protects against oxidative stress in neurons but is inactivated by S-nitrosylation) [88], and αSynuclein, with Lewy bodies enriched with the nitrated species [89, 90]. This evidence concerns the gene P4HB and Parkinson disease.