TRAF6 and prostate cancer: In parallel, in prostate cancer cells, TRAF6 can polyubiquitylate the membrane-embedded protease presenilin-1 (PS-1), which performs a second proteolytic cleavage on TGFβRI, causing the release of the complete intracellular domain (ICD) of the receptor, and stimulating the translocation of the TGFβRI ICD to the nucleus [212].