KLKB1 and nephrotic syndrome: To date, our group has evaluated several serine proteases such as urokinase-type plasminogen activator (encoded by Plau), plasminogen (Plg), plasma kallikrein (Klkb1) or factor VII activating protease (Habp2) with regard to their relevance for proteolytic ENaC activation in experimental nephrotic syndrome [4, 8, 20, 36].