As protein levels of TGFbRI and TGFbRII were comparable between OPN−/−TRAMP NE tumors and TRAMP adenocarcinoma (not shown), we focused on proteins downstream the TGFβ pathway, particularly Smad2 and Smad3, which are crucial mediators of TGFβ activity in PCa [26]. Here, SMAD3 is linked to posterior cortical atrophy.