Caldesmon

Caldesmon (CALD) is a protein that binds to actin and calmodulin in smooth muscle cells. It can tightly bind to actin and tropomyosin in thin filaments to inhibit the binding of actin to myosin of thick filaments, thereby suppressing smooth muscle contraction. In clinical practice, CALD is mainly applied in the diagnosis of various smooth muscle derived tumors such as glomangioma, gastrointestinal leiomyoma, and retroperitoneal leiomyosarcoma. Especially in uterine tumors, CALD is not expressed in stromal sarcoma, lowly expressed in leiomyosarcoma but highly expressed in bizarre or cellular leiomyoma, which makes it become an assisting differential biomarker. Meanwhile, some research found that CALD can be expressed in gastrointestinal stromal tumor (GIST), and its positive patients have longer progression free survival time, indicating that GIST has a tendency towards muscle differentiation, which may be an advantageous factor for patient prognosis. In addition, CALD is considered as an effective indicator for distinguishing between thymic epithelioid mesothelioma (+) and lung adenocarcinoma (-).