Immunohistochemical staining of smooth muscle α-actin in control ( a ) and injured carotid arteries ( b ) of an apoE(−/−) mouse. Paraffin sections were obtained 14 days after mechanically induced injury of the mouse carotid artery. The sections were incubated with a monoclonal antibody against α-smooth muscle cell α-actin at a dilution of 1:3,000. Immunoreactivity was detected by incubation with 0.5% biotinylated anti-mouse IgG, followed by incubation with avidin-peroxidase complex and visualized with 3,3′-diaminobenzidine. Scale bar, 50 μm.