The protein dosage of PEA3 subfamily of ETS transcription factors ETV1, ETV4, and ETV5 is regulated through both transcription and ubiquitylation-mediated protein degradation by E3 ubiquitin ligase COP1, a tumor suppressor in both human prostate cancer and in GEM models of prostate cancer (22–24). This evidence concerns the gene ETV1 and prostate cancer.