F2R and diabetic kidney disease: When it comes to podocyte injury, while a recent study demonstrated that plasmin is also involved in the podocyte injury in doxorubicin-induced nephropathy [18], a coagulation serine protease thrombin has been reported to injure podocytes in nephrotic rats and diabetic nephropathy rats by activating PAR-1 and PAR-4 [18,41].