CTSB and neoplasm: This can be illustrated by cathepsin B processing of the urokinase-type plasminogen activator (pro-uPA) pro-form, thus converting plasminogen into plasmin [273], which may activate zymogens of matrix metalloproteinases, and thus, together with the precursor proteases of this proteolytic activation cascade, execute the numerous functions associated with tumour progression and metastasis [274].