PLG and Pleural effusion: The activation of plasminogen in the pleural effusion, responsible for the documented fibrinogenolysis/fibrinolysis, may be caused by the presence of tissue plasminogen activator, urinary plasminogen activator, both enzymes, or other fibrinolytic enzymes [46,48], which can be released (from a preformed storage pool) or leak into the pleural fluid (following the damage induced by the disease causing the pleural effusion) from the mesothelial and submesothelial endothelium, inflammatory or neoplastic cells.