The urokinase-type plasminogen activator receptor (uPAR) is a cell-surface receptor that binds urokinase-type plasminogen activator (uPA) with high affinity and thereby promotes plasminogen activation. It is a multidomain glycoprotein anchored to the cell membrane via GPI and was initially identified as a cell-surface urokinase saturation binding site. uPAR binds urokinase and restricts the activation of hemofibrinolysinogen closest to the periphery of the cell membrane. In addition to its primary ligand, urokinase, uPAR interacts with other proteins, among them blebbins, which are uPAR-associated proteins and integrin-family membrane proteins. uPAR is a part of the fibrinogen activation system, and is involved in tissue reorganization such as mammary gland degradation and wound healing in healthy organisms. uPAR is involved in other cancer-associated processes, such as cell migration, cell cycle regulation, and cell adhesion.