Studies have indicated that TMPRSS2:ERG fusion may co-operate with the loss of the tumor suppressor PTEN and the concomitant activation of AKT to promote the progression of prostate cancer from high-grade prostatic intraepithelial neoplasia (PIN) to invasive prostate carcinoma [50,51]. The gene discussed is PTEN; the disease is prostate intraepithelial neoplasia.