EGF family of growth factors: essential roles and functional redundancy in the nerve system.

Evidence has suggested that the epidermal growth factor receptor (EGF-R) and its ligands are important regulators for development and maintenance of various tissues including the nerve system. Gene knockout, transgenic or other in vivo and in vitro studies have demonstrated that these molecules, produced by neurons and glial cells, play important roles in regulating neural/glial precursor cell or stem cell proliferation, migration, differentiation and survival, in maintaining tissue homeostasis, and in regulating CNS gliosis and peripheral nerve injury responses. These studies have revealed that, despite a possible functional redundancy among the individual EGF family ligands, collectively EGF-R ligands are required for development and maintenance of the nerve system.