Extracellular proteolytic cleavage by urokinase is required for activation of hepatocyte growth factor/scatter factor - Naldini, L; Tamagnone, L; Vigna, E; Sachs, M; Hartmann, G; Birchmeier, W; Daikuhara, Y; Tsubouchi, H; Blasi, F; Comoglio, PM (EMBO J, 1992)