ERG and prostate intraepithelial neoplasia: The TMPRSS2:ERG fusion gene is not present in non-neoplastic prostate epithelium, but has been described in high-grade prostatic intraepithelial neoplasia (HGPIN) lesions (Cerveira et al., 2006; Park et al., 2010), suggesting that it might represent an early event in the development of prostate cancer (Perner et al., 2007).