Alterations in endothelial cell-extracellular matrix interactions are central to the process of angiogenesis. We have investigated the effect of wound-induced two-dimensional migration, basic fibroblast growth factor (bFGF), transforming growth factor-beta 1 (TGF-β1) and leukemia inhibitory factor (LIF) on expression of the α₅β₁ integrin in endothelial cells. In multiple-wounded monolayers of bovine microvascular endothelial (BME) cells, an increase in mRNA and total protein for both α₅ and β₁ subunits was observed, and this could be correlated with a reduction in cell density but not proliferation, both of which are induced following wounding. Although as previously reported, the α₅ subunit was increased when cells were exposed to TGF-β1 alone, co-addition of bFGF and TGF-β1 resulted in a striking synergistic induction of α5, with no significant changes in the expression of β1. In contrast, the α5 subunit was decreased by LIF in bovine aortic endothelial but not in BME cells. These findings suggest that quantitative alterations in α5 and β1 integrin subunit expression modulate the adhesive and migratory properties of endothelial cells during angiogenesis.