An experimental study used smooth muscle cells from rat thoracic aorta (A7r5 cell line) to analyze the influence of different exposure times (up to 48 h) and concentrations of DEHP (2, 3.5, 7, 10.5, 14, 17.5 ppm) on matrix metalloproteinase (MMP)-2 and MMP-9, that are related with atherosclerosis. The gene discussed is MMP2; the disease is atherosclerosis.