PLAU and lung cancer: Components of the uPA system such as u-PA, plasminogen activator inhibitor-1 (PAI-1) and urokinase-type plasminogen activator receptor (uPAR) are overexpressed in a variety of cancer types, most notably in breast cancer (22), but also in lung cancer (17,23) and malignant mesothelioma (18,24) and correlate with cancer progression, metastasis and poor prognosis.