Platelet-derived growth factor (PDGF)-BB elicits a migratory response including reorganization of the actin cytoskeleton in different cell types. Here we have investigated the effects of PDGF-BB stimulation on ß 1 integrin containing focal adhesions in human diploid fibroblasts adhered to collagen type I. Stimulation with PDGF-BB dissociated focal adhesions and relocated ß1 integrins from focal adhesions to the periphery of the cells. These changes were rapid and transient in character. Relocation of ß1 integrins was prevented by inhibitors of phosphoinositide-3-kinase and protein kinase C. PDGF-BB stimulated fibroblasts exhibited an increased diffusion coefficient of cell surface ß1 integrins as determined by fluorescence recovery of photobleaching. The cell surface expression of ß1 integrins was not changed after stimulation with PDGF-BB. Our data suggest that PDGF-BB increases the dynamic properties of cell-surface ß1 integrins, which most likely are important for the migratory response elicited by PDGF-BB. © 2003 Elsevier Inc. All rights reserved.