Objective— We investigated the comparative roles of mitogen-activated protein (MAP) kinases, including c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38, in vascular smooth muscle cell (VSMC) proliferation, migration, and gene expression.

Methods and Results— VSMCs were infected with recombinant adenovirus containing dominant-negative mutants of ERK, p38, and JNK (Ad-DN-ERK, Ad-DN-p38, and Ad-DN-JNK, respectively) to specifically inhibit the respective MAP kinases and then stimulated with platelet-derived growth factor (PDGF)-BB. Ad-DN-ERK attenuated PDGF-BB–induced VSMC proliferation more potently than Ad-DN-p38 or Ad-DN-JNK, indicating the dominant role of ERK in VSMC proliferation. Ad-DN-ERK, Ad-DN-p38, and Ad-DN-JNK similarly inhibited PDGF-induced VSMC migration. Ad-DN-ERK and Ad-DN-JNK suppressed PDGF-BB–induced downregulation of cyclin-dependent kinase inhibitor p27^Kip1, whereas Ad-DN-p38 decreased PDGF-BB–induced upregulation of p21^Cip1. Ad-DN-ERK inhibited PDGF-BB–induced plasminogen activator inhibitor type-1 (PAI-1), monocyte chemoattractant protein-1, and transforming growth factor-β₁ expressions, Ad-DN-p38 blocked monocyte chemoattractant protein-1 and transforming growth factor-β₁ expression but not PAI-1, whereas Ad-DN-JNK suppressed only PAI-1 expression. Moreover, in vivo gene transfer of Ad-DN-p38 to rat carotid artery caused the inhibition of intimal hyperplasia by balloon injury, indicating the involvement of p38 in vascular remodeling in vivo.

Conclusions— We propose that these 3 MAP kinases participate in vascular diseases via differential molecular mechanisms and are new therapeutic targets for treatment of vascular diseases.