NTF4, also known as neurotrophin 4, is a member of a family of neurotrophic factors neurotrophins that control survival and differentiation of mammalian neurons. This protein is ubiquitous and less influenced by environmental signals. While knock-outs of other neurotrophins including nerve growth factor, brainderivedneurotrophic factor, and neurotrophin 3 prove lethal during early postnatal development, NTF4-deficient mice only show minor cellular deficits and develop normally to adulthood.