The article provides an overview of the plasminogen activator (PA) and plasmin system, highlighting its role in extracellular matrix (ECM) degradation and its regulation. PAs, primarily urokinase-type PA (uPA) and tissue-type PA (tPA), are serine proteases that activate plasminogen to form the active enzyme plasmin. Plasminogen activator inhibitors (PAIs) such as PAI-1 and α2-antiplasmin regulate the activity of PAs. The article discusses the binding of PAs and plasminogen to cell surfaces, particularly the uPA receptor, which plays a crucial role in spatially controlling proteolysis. The regulation of PA and PAI synthesis is influenced by various signal transduction pathways, including glucocorticoids and cAMP. The article also explores the physiological and pathological functions of PAs, including their roles in embryonic development, ovulation, inflammation, wound healing, angiogenesis, and neoplasia. Additionally, it suggests that PAs may participate in the activation and processing of growth factors and hormones, and could influence synaptic plasticity. The dynamic nature of the PA/plasmin system and its involvement in a wide range of biological processes underscores the importance of understanding its functions and regulation.The article provides an overview of the plasminogen activator (PA) and plasmin system, highlighting its role in extracellular matrix (ECM) degradation and its regulation. PAs, primarily urokinase-type PA (uPA) and tissue-type PA (tPA), are serine proteases that activate plasminogen to form the active enzyme plasmin. Plasminogen activator inhibitors (PAIs) such as PAI-1 and α2-antiplasmin regulate the activity of PAs. The article discusses the binding of PAs and plasminogen to cell surfaces, particularly the uPA receptor, which plays a crucial role in spatially controlling proteolysis. The regulation of PA and PAI synthesis is influenced by various signal transduction pathways, including glucocorticoids and cAMP. The article also explores the physiological and pathological functions of PAs, including their roles in embryonic development, ovulation, inflammation, wound healing, angiogenesis, and neoplasia. Additionally, it suggests that PAs may participate in the activation and processing of growth factors and hormones, and could influence synaptic plasticity. The dynamic nature of the PA/plasmin system and its involvement in a wide range of biological processes underscores the importance of understanding its functions and regulation.