Any of a family of proteins that are crucial components of the basal lamina, the dense fibrous layer of the basement membrane underlying most epithelial and endothelial cells. Laminins are large cross-shaped molecules that bind the collagen fibres of the lamina to adjoining cells and to the looser surrounding connective tissue, thus helping to create and stabilize the basic fibrous network. This is accomplished through multiple binding sites on the laminin molecule, each specific for different components. Laminins have vital roles not only in maintaining the integrity of mature tissues but also in organizing cells into tissues during embryonic development.