TMPRSS2 and posterior cortical atrophy: Using a nested PCR-based approach, we were able to show that tumour exosomes carry genetic information specific for PCa, and as a proof-of-principle we used tumour exosomes to detect two PCa mRNA biomarkers, PCA-3 and TMPRSS2:ERG (Hessels et al, 2007; Laxman et al, 2008).