Alpha-smooth muscle actin (α-SMA) is a protein that is prominently found in smooth muscle cells and is encoded by the ACTA2 gene. It is one of the six actin isoforms and plays a crucial role in the contractile function of smooth muscle tissues. In the context of histology, α-SMA is often used as a marker to identify and study smooth muscle cells, myofibroblasts, and other contractile cells in various tissues.
