LAMB3 is a protein that encodes the β3 chain of laminin; it is primarily involved in the formation of laminin 332 and constitutes a key component of the basal membrane in skin and mucosal epithelia. This protein is found at the junction between the epidermis and dermis, where it facilitates the adhesion and migration of epithelial cells as well as the establishment of the epidermal barrier, thereby maintaining the integrity of the skin structure. Mutations that impair the function of the LAMB3 gene can disrupt the connections in the basal membrane, leading to dystrophic epidermolysis bullosa, a condition characterized by blisters and erosions in the skin. In the field of oncology, abnormally high expression of LAMB3 can alter the extracellular matrix, promote epithelial-mesenchymal transition, and enhance the invasiveness and metastatic capacity of cancer cells; it often serves as a marker of poor prognosis in melanoma, lung cancer, and gastrointestinal tumors.