Laminin–111 (iMatrix-111) is a protein of the type known as laminin isoforms. It was among the first of the laminin isoforms to be discovered. The "111" identifies the isoform's chain composition of α1β1γ1. This protein plays an important role in embryonic development. Injections of this substance are used in treatment for Duchenne muscular dystrophy, and its cellular action may potentially become a focus of study in cancer research.

Laminin 111 supports the survival, proliferation, and differentiation of many different cell types in vitro. However, its distribution after birth is restricted to only a few tissues, such as the brain and kidney. Many of the cultivated cell types would not encounter this protein naturally in vivo and it is advisable to match your specific cell type to the laminin naturally expressed by this cell, improving the cell culture. During development, Riechert’s membrane supporting the extraembryonic trophoblasts express laminin 111. Reichert’s membrane is essential for epiblast differentiation, which is essential for the formation of the three embryonic germ layers by pluripotent cells in the inner cell mass.

In the adult, laminin α1 chain expression is relatively restricted and is only present in some epithelial basement membranes, and primarily found in tissues such as the eye, liver, and kidney, whereas hardly expressed at all in endothelial, adipose, nervous, or muscle tissues (Ekblom, 2003; Virtanen, 2000).

In addition to inducing different cell signaling cascades, laminin 111 is known to co-signal with various growth factors in a cell type dependent manner. This may be an explanation for the major biological effects that laminin 111 exerts on a wide selection of cell types.