ERG and prostate cancer: According to this classification based on the analysis of molecular abnormalities observed in a large set of localized prostate cancers the tumor foci were classified into one of the seven molecular subgroups based on ETS gene fusion status (ERG, ETV1, ETV4, or FLI1 fusions) or somatic mutations of either SPOP1 or FOXA1 or IDH1 genes.