ERG and neoplasm: Our finding that ERG is associated with ETV-4 is highly intriguing, as ETV-4 is known to be rearranged in PCa, similar to ERG (2–4,39), combined with a recent report showing the occurrence of multiple ETS rearrangements within one prostate gland, within the same tumor focus and within the same nucleus (27), which may imply a potential cooperation or interaction between rearranged ETS genes in PCa.