Smooth muscle cell (SMC) proliferation that results in neointima formation is implicated in the pathogenesis of atherosclerotic plaques and accounts for the high rates of restenosis that occur after percutaneous transluminal coronary angioplasty, a widespread treatment for coronary artery disease. Endothelial lesions trigger intense proliferative signals to the SMCs of the subintima, stimulating their reentry into the cell cycle from a resting G0state, resulting in neointima formation and vascular occlusion. Cellular proliferation is negatively controlled by growth-regulatory or tumor-suppressor genes, or both, such as the retinoblastoma gene family members (RB/p105, p107, RB2/p130). In the present study, we show thatRB2/p130inhibited SMC proliferation in vitro and in vivo. We used the rat carotid artery model of restenosis to demonstrate that adenovirus-mediated localized arterial transduction ofRB2/p130at the time of angioplasty significantly reduced neointimal hyperplasia and prevented restenosis. Furthermore, the ability of pRb2/p130 to block proliferation correlated with its ability to bind and sequester the E2F family of transcription factors, which are important mediators of cell cycle progression. These results imply thatRB2/p130could be an important target for vascular gene therapy.