REGULATION OF SMOOTH MUSCLE CELL (SMC) GROWTH: Accelerated growth of SMC is known to play an integral role in atherosclerotic lesion formation as well as post-angioplasty restenosis, and is a characteristic feature in arteries of hypertensive patients and animals. There has thus been extensive interest in defining both positive and negative regulators of SMC growth, and many factors have been identified that may play a role in this process. REGULATION OF DIFFERENTIATED SMC: Despite clear evidence that the differentiated state of the intimal SMC is altered in atherosclerotic disease, and that this is likely to play a key role in lesion development, relatively little is known about the mechanisms and factors that regulate the differentiated state of SMC. Extrinsic factors (local environmental cues) make an important contribution to the regulation of the differentiated state of the vascular SMC. Molecular mechanisms control the expression of genes encoding for proteins such as smooth muscle alpha-actin and smooth muscle myosin heavy chain that are selective or specific for SMC, and which are required for the SMC principal differentiated function, contraction.