Extracellular matrix (ECM) proteins are a group of proteins that are secreted by cells and form the structural framework of tissues and organs outside of the cells. They provide physical support and mechanical strength to tissues, as well as help to regulate cell behavior and signaling. ECM proteins include fibrous proteins such as collagen and elastin, glycoproteins such as laminin and fibronectin, and proteoglycans. They play important roles in a variety of biological processes, including cell adhesion, migration, differentiation, and tissue development and repair. Dysregulation of ECM protein expression and function has been implicated in various diseases, including cancer, fibrosis, and cardiovascular disease.