Smooth muscle cells (SMCs) are specialised, non-striated muscle cells found in the walls of hollow organs and blood vessels, responsible for involuntary contractions that regulate vessel diameter and organ motility. Their function is critical in maintaining vascular tone and blood pressure, as well as facilitating processes like peristalsis in the gastrointestinal tract. Dysfunction or abnormal proliferation of SMCs contributes to pathological conditions such as atherosclerosis, where they play a key role in plaque formation and vessel narrowing.