PRKN (Parkin, PARK2) is an E3 ubiquitin ligase involved in ubiquitination, the promotion of cell survival, autophagy and mitophagy. Mutations in PRKN result in mitochondrial dysfunction and are thought to lead to juvenile and early-onset Parkinson disease (AR-JP). Additionally, PRKN mutations, loss of function or loss of expression events are frequent in glioblastoma, lung cancers and other malignancies and are correlated with worse prognosis. In immunohistochemistry, PRKN has high cytoplasmic and nuclear positivity in the brain, and is also expressed in other tissues including the kidney, testes, muscle, lung, gastrointestinal tract, liver, and thyroid and adrenal glands. References: The FEBS Journal. 282 (11): 2076–88, PMID: 25712550; Nature Genetics. 42 (1): 77–82, PMID: 19946270;