PLAU and neoplasm: Among these markers, the urokinase plasminogen activator (uPA) system, which is primarily composed of uPA (a serine protease), uPA receptors (uPAR), and several inhibitors/modulators of uPA (especially plasminogen activator inhibitor 1 [PAI-1]), have attracted special attention as they serve as fundamental mediators of signaling pathways contributing to tumor microenvironment regulation [2].