ETV4 and prostate carcinoma: Genetic rearrangements that lead to transcriptional up-regulation of ETS family transcription factors including ERG and three highly conserved polyomavirus enhancer activator 3 (PEA3) subfamily members—ETV1, ETV4, and ETV5—are prevalent and mutually exclusive in prostate cancer; they occur early in the natural history of the disease (2–6).