The current assay should facilitate a thorough compilation of the gene fusion variants in primary prostate specimens, which may be useful for stratifying the aggressiveness of prostate cancer (13) . In this regard, fusion variants of EWS with another member of the ETS family, FLI1, have been shown to be an independent predictor of disease progression in Ewing's sarcoma (40, 41) . It will be of interest to compare in transfected cells the biological activities of the different TMPRSS2:ERG variants from patients with contrasting clinical outcomes (41) .