Table 1.

Summary of some known actions of transforming growth factor β (TGF-β) family members in the nervous system

TGF-β family member	Effects of antagonism	Synergistic effects
BMPs	Induction of nervous system Floor plate induction (BMP-4 and BMP-7) Oligodendrogenesis (BMP-2/BMP-4) Neurogenesis in olfactory epithelium	Roof plate induction (BMP-4 and BMP-7) Anterior neural tissue specification (BMP-5 and BMP-7) Dorsoventral patterning of the nervous system (BMP-4, BMP-6, and BMP-7) Neurogenesis (BMP-2, BMP-4, and BMP-6) Astrocytogenesis (BMP-2 and BMP-4) Cholinergic neuron specification (BMP-9) Guidance of commissural axons (BMP-7) Dendritic growth Neuronal migration Induction of neurotrophin dependence Apoptosis of stem/progenitor cells
Nodal	Induction of nervous system	Induction of floor plate Differentiation of hypothalamic neurons
Activins	Induction of nervous system	Specification of rod photo receptors
GDFs	Neurogenesis in olfactory epithelium (GDF-11)	Specification of dorsal neurons (GDF-7) Neurogenesis in olfactory epithelium (GDF-7) Guidance of commissural axons (GDF-7)
TGF-βs	Microglial activation (TGF-β1)	Neurotrophic for dopaminergic and Purkinje neurons (TGF-β2 and TGF-β3) Neuronal differentiation in olfactory epithelium (TGF-β1 and TGF-β2) Differentiation of oligodendrocytes Neuronal migration (TGF-β1 and TGF-β2) Axon elongation (TGF-β1 and TGF-β2) Synaptogenesis Astrogliosis after injury (TGF-β1)