Background：Laminins, a family of extracellular matrix glycoproteins, are the major noncollagenous constituent of basement membranes. They have been implicated in a wide variety of biological processes including cell adhesion, differentiation, migration, signaling, neurite outgrowth and metastasis. Laminins are composed of 3 non identical chains： laminin alpha, beta and gamma （formerly A, B1, and B2, respectively） and they form a cruciform structure consisting of 3 short arms, each formed by a different chain, and a long arm composed of all 3 chains.
