PRKN and Familial prostate cancer: In a study on the role of the ubiquitin-proteasome network in prostate cancer, the proteasome genes Psmc4 and Psmb5 and the E3 ubiquitin ligase NEDD4L were found to be significantly and consistently upregulated in prostate cancer cells compared to the corresponding adjacent normal prostate tissue, suggesting a pivotal role for Psmc4 in prostate tumorigenesis [70].