ERG and neoplasm: Previously, the TCGA landmark paper (11) has categorized pri-PCa into three clusters based on tumor transcriptomes (mRNA clusters 1–3), and reported that, genomically, 74% of pri-PCa belonged to either one of seven subtypes defined by gene fusions (ERG, ETV1/4 and FLI1) or mutations (SPOP, FOXA1 and IDH1).