PLAU and cancer: A tight connection between the uPA/uPAR system and TGF-β has also been observed: TGF-β up-regulates the expression of both uPA and uPAR; uPA binds uPAR and activates plasminogen, which, in turn, can activate latent TGF-β, participating to a positive loop contributing to the development of EMT in cancer cells [68,69].