Here we expand on our recent findings that loss of parkin RBR E3 ubiquitin protein ligase (PRKN, best known as PARK2)—which is genetically linked to PD—promotes cancer progression via redox-mediated inactivation of phosphatase and tensin homolog (PTEN) by S-nitrosylation. The gene discussed is UBE2E3; the disease is Parkinson disease.