['Atherosclerosis is the underlying pathological process of most cardiovascular disease. Thrombin is a serine protease which can activate protease activated receptors (PAR) on vascular smooth muscle cells (VSMC) to elicit cellular responses that can contribute to the pathogenesis of atherosclerosis. Human atherosclerosis commences with the binding and retention of lipoproteins by the glycosaminoglycan (GAG) chains of chondroitin/dermatan sulfate proteoglycans. The potential effects of thrombin on the synthesis and structure of CS/DS proteoglycans produced by VSMCs was investigated.', 'VSMCs were derived from human internal mammary arteries. Proteoglycan synthesis was assessed by [(35)S]sulfate and [(3)H]glucosamine incorporation. Proteoglycan size was assessed by SDS-PAGE and size exclusion chromatography.'] Does thrombin regulate vascular smooth muscle cell proteoglycan synthesis via PAR-1 and multiple downstream signalling pathways?