uPAR is a highly glycosylated GPI-anchored membrane protein. In addition to the membrane-anchored form, uPAR is released from the plasma membrane by cleavage of the GPI anchor and can be found as a soluble form (suPAR). uPAR contains three homologous domains (D1-D3) of which the N-terminal one (D1) represents the uPA-binding domain. After binding to uPAR, uPA cleaves plasminogen, generating the active protease plasmin which is involved in a wide variety of physiologic and pathologic processes. In addition to regulating proteolysis, uPAR has important function in cell adhesion, migration and proliferation. Studies reveal that uPAR expression is elevated during inflammation and tissue remodelling and in many human cancers, in which it frequently indicates poor prognosis. suPAR has been detected in plasma, and increased plasma concentrations of suPAR have been found in patients with some advanced cancers.