Caldesmon is a key member of the actin-binding protein family, ubiquitously expressed in smooth muscle cells and various mesenchymal cells, and functions as a core regulator of cytoskeletal contraction and cellular motility. By binding to actin, myosin and calmodulin, Caldesmon modulates actin filament assembly and stability, inhibits excessive smooth muscle contraction, maintains cytoskeletal homeostasis, and participates in multiple biological processes including cell migration, morphological remodeling, smooth muscle contraction and relaxation, and cell division. It contains high-molecular and low-molecular isoforms, specifically marking smooth muscle differentiation and cell migratory activity respectively. Its aberrant expression is closely associated with smooth muscle lesions, tumor invasion and metastasis, and tissue fibrosis, serving as a vital biomarker for pathological typing and tumor prognosis evaluation.