PLE-5704

A 60-year-old man died secondary to coronary artery disease. During autopsy, the lumen of the coronary arteries was covered with fibrous plaques, and an area with ruptured plaque and superimposed thrombosis. Sections from these abnormal areas revealed a fibrous cap and a central core (largely lipid) core with an area showing disruption of the fibrous cap with thrombosis. Which one of the following substances promotes atherosclerosis by stimulating smooth muscle cells to migration and proliferation in sites of endothelial injury?