When antibodies to fibronectin are injected into the developing chick embryo, they alter the migration of cranial NC cells, but not trunk NC cells. These experiments indicate that different ECM proteins are important for different cells and migration routes. The defective genes can be cloned. The similarity of these mutant phenotypes indicates that the two genes function to regulate similar processes. Stem cell factor is secreted by tissues along the migration route and stimulates NC cells to divide.
Kit function is required in the NC cells.
Ephrins bind Eph receptors, which have tyrosine kinase domains. Activating the Eph receptor in NC cells causes them to stop migrating.