Beta-catenin is a protein involved in cell-cell adhesion and proliferation. In neoplastic diseases, defects in the regulation of the cellular beta-catenin content and cytoplasmic accumulation of the protein contribute to the uncontrolled cell proliferation and migration. Whether beta-catenin plays a role in the controlled proliferative and migratory responses to injury, eg, of vascular endothelial cells during neovascularization after myocardial infarction (MI), is not known. In the present study, we examined the localization of beta-catenin in the infarcted rat heart at different time points after MI. Cytoplasmic beta-catenin was observed in the endothelial cells of the newly formed and pre-existing blood vessels in the infarct area in the first week after MI, but not in the uninjured parts of the heart and not at later time points. Adenomatous polyposis coli (APC) protein was also detected; interaction of APC with beta-catenin has been reported to be critical in epithelial tube formation in vitro. Moreover, the expression of dishevelled-1, an upstream regulatory molecule of the cellular beta-catenin content, was observed in vascular endothelial cells in the infarct area. These findings suggest a role for the beta-catenin-APC complex in the proliferation and migration of vascular endothelial cells during neovascularization of the infarct area.