Abstract
Smooth muscle cells are widespread in the human body, found in a range of tissues from the vasculature to the gut, airways, bladder and so on. They can be found as isolated cells or organised into syncytia (groups of cells). The organisation of the contractile cytoskeleton (smooth muscle actin and myosin filaments) is less well understood than that of striated (cardiac and skeletal) muscle. This review aims to explore what is known, the potential effects of mutations in smooth muscle actin, myosin and tropomyosin and how they lead to disease, and to highlight what we have still to learn about the smooth muscle contractile cytoskeleton.