Up-regulation of Urokinase-type Plasminogen Activator by Insulin-like Growth Factor-i Depends upon Phosphatidylinositol-3 Kinase and Mitogen-activated Protein Kinase Kinase Abstract Elevated Levels of Urokinase Plasminogen Activator-1 (upa) and the Insulin-like Growth Factor-i Receptor (igf-ir) Are