urokinaseinduced signaling in human vascular smooth muscle cells is mediated by pdgfrbeta urokinase upainduced signaling in human vascular smooth muscle cells vsmc elicits important cellular functional responses such as cell migration and proliferation however how intracellular signaling is linked to glycolipidanchored upa receptor upar is unknown we provide evidence that upar activation by upa induces its association with plateletderived growth factor receptor pdgfrbeta the interaction results in pdgfindependent pdgfrbeta activation by phosphorylation of cytoplasmic tyrosine kinase domains and receptor dimerization association of the receptors as well as the tyrosine kinase activity of pdgfrbeta are decisive in mediating upainduced downstream signaling that regulates vsmc migration and proliferation these findings provide a molecular basis for mechanisms vsmc use to induce upar and pdgfrdirected signaling the processes may be relevant to vsmc function and vascular remodeling