Urokinase Plasminogen Activator Receptor: A Functional Integrator of Extracellular Proteolysis, Cell Adhesion, and Signal Transduction

The urokinase plasminogen activator receptor (uPAR) is a cell surface receptor involved in amultitude of physiologic and pathologic processes. uPAR regulates simultaneously a branch of the plasminogen activator system and modulates cell adhesion and intracellular signaling by interacting with extracellular matrix components and signaling receptors. Themultiple uPAR functions are deeply interconnected, and their integration determines the effects that uPAR expression triggers in different contexts. The proteolytic function of uPAR affects both the signaling and the adhesive functions of the receptor, whereas these latter two are closely interconnected. This review focuses on the molecular mechanisms that connect and mutually regulate the different uPAR functions.