The PIM-1 (proto-oncogene serine/threonine-protein kinase) protein is an epithelial-derived, integral membrane serine protease. This protease forms a complex with the Kunitz-type serine protease inhibitor, HAI-1, and is activated by sphingosine 1-phosphate. PIM-1 cleaves and activates hepatocyte growth factor/scattering factor (HGF) as well as urokinase plasminogen activator (uPA). Such downstream targets implicate this serine protease as an epithelial membrane trigger for a sequential protease cascade.
