Aim To investigate whether or not the time course of the cellular proliferation and aPoptotic cell deatk is re1ated with expresion of some oncoproteins, c-Myc, c-Fos, Bcl-2 and P53, in miniswine atherosclerotic ili- ac arteries following balloon angioplasty.Methods Atherosclerotic lesions developed by endothelial denudation combined with atherogenic di-et. Balloon angioplasty was performed in the right il-iac artery of atherosclerotic miniswines. After 1, 3,8, 14, 30, and 90 days ; respectively, the experimen-tal animals were killed and iliac arteries were re-moved. Immunohistochemical assays were applied by using primary antibodies against P53, c-Myc. c-Fos,and Bcl-2. With 3-3'-diaminobenzidine (DAB) the sec-tions were stained. Cell proliferation was determined with an antibody to the proliferating cell nuclear antigen (PCNA). comtbined with SMC-specific anti-body. The presence of apoptotic cells was determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL).ResultS Percentages of PCNA-positive cells in the intirna vs mfdia were 22. 4% vs 21. 6%, 27. 8% vs 27. 5%, 30. 6% vs 21. 2% at 1, 3, and 8 days, re- spectively, after balloou angioplasty- Percentages of TUNEL-positive cells in the intima vs media were 3.oN vs 0. 9%, 4. 3% vs 1.4%, 16.0% vs 1. 9% at 1,3, and 8 days, rspectively. Coefficients of linear corre-lation of PCNA witb c -MyC and c-Fos were o. 6472 and 0. 6362 (p<0. 05), and TUNEL with Bcl-2 and P53, -0. 7538 and 0. 8447 (p<0. 05). respectively.Angioplastied and control vessels 8howed different lev-els of peNA and TUNEL, and also different expres-sion levels of c-Myc, c-Fos, Bcl-2, and P53 in cells.Concluslons Arterial injury may result in the in-crease of cell prc1iferation and apoptotic cell death in botb intima and media. Cell proliferation and apoptosis in tke injured vessels associated with the expression of the immediate-early gene (c-myc, c-fos), proto-onco-gene (bcl-2) and relative gene (p53).