Characteristic features of the nervous system converge into network formation during the development. The neurons recognize precisely their target cells and form synapses, and these steps are complex, but well organized spatially and temporally. The neurite promotion from the neurons is one of the most important events for synapse formation. It is well known that extracellular matrix proteins such as laminin and their receptors, and cell adhesion molecules such as NCAM participate in cell migration and synaptic formation. We have isolated a neurite outgrowth factor (NOF) which promotes neurite outgrowth from various neurons and belongs to laminin family, and also its receptor which is identified to be an immunoglobulin superfamily protein by cDNA cloning. This ligand-receptor system is a unique example that a receptor with immunoglobulin-like structure interacts with an extracellular matrix protein.