ERG and prostate cancer: It is well established that TMPRSS2 is highly expressed in prostate epithelial cells, and the TMPRSS2-ERG [erythroblast transformation-specific transcription factor (ETS) -related gene, ERG] fusion gene is frequently expressed in benign prostatic hyperplasia and primary prostate cancer tissues (Perner et al., 2007; FitzGerald et al., 2008; Park et al., 2014).