PARP1 and prostate cancer: In prostate cancer, Ipsen et al. (2022) determined that deletion of PARP1, ARH3 (ADP-ribosylserine hydrolase), tryptophan 5-monooxygenase activation protein epsilon, and ubiquitin protein ligase E3 component n-recognin 5 resulted in olaparib resistance, where PARP1 or ARH3 knockdown resulted in reduced autophagy and increased cellular resistance, suggesting that low ARH3 expression is an independent prognostic indicator.