The purpose of this study was to determine the effect of the peroxisome proliferator-activated receptor γ-(PPARγ) ligands troglitazone (TRO), rosiglitazone (RSG), and 15-deoxy-Δ prostaglandin J2 (15d-PGJ2) on vascular smooth muscle cell (VSMC) migration directed by multiple chemoattractants. Involvement of mitogen-activated protein kinase (MAPK) in migration also was examined, because TRO was previously shown to inhibit nuclear events stimulated by this pathway during mitogenic signaling in VSMCs. Migration of rat aortic VSMCs was induced 5.4-fold by PDGF, 4.6-fold by thrombin, and 2.3-fold by insulin-like growth factor I (IGF-I; all values of p< 0.05). The PPARγ ligands 15d-PGJ2, RSG, or TRO all inhibited VSMC migration with the following order of potency: 15d-PGJ2> RSG> TRO. Inhibition of MAPK signaling with PD98059 completely blocked PDGF-, thrombin-, and IGF-I-induced migration. All chemoattractants induced MAPK activation. PPARγ ligands did not inhibit MAPK activation, suggesting a nuclear effect of these ligands downstream of MAPK. The importance of nuclear events was confirmed because actinomycin D also blocked migration. We conclude that PPARγ ligands are potent inhibitors of VSMC migration pathways, dependent on MAPK and nuclear events. PPARγ ligands act downstream of the cytoplasmic activation of MAPK and appear to exert their effects in the nucleus. Because VSMC migration plays an important role in the formation of atherosclerotic lesions and restenosis, PPARγ ligands like TRO and RSG, which ameliorate insulin resistance in humans, also may protect the vasculature from diabetes-enhanced injury.