Laminins are heterotrimeric, noncollagenous glycoproteins composed of combinations of five known alpha, four beta and three gamma chains in mammals. One alpha, beta and gamma subunit self-assembles to form at least 15 coiled-coil heterotrimers. Through specific interactions with integrins, dystroglycan, and other receptors, laminins contribute to cell differentation, cell shape and migration, maintenance of tissue phenotypes and survival. Some subunits, such as Laminin gamma1 (Laminin B2), are present in several laminins; Laminin-1 (EHS laminin), Laminin-2 (merosin), Laminin-3 (S-laminin), Laminin-4 (S-merosin), Laminin-6 (K-laminin) and Laminin-7 (KS-laminin). Others, such as the beta3 and gamma2 subunits, occur in only one known combination (e.g. with alpha3 in Laminin-5 / Epiligrin).