Neurotrophic factor unrelated to the neurotrophins, q.v. Cytosolic peptide produced by Schwann cells in the peripheral nervous system and by astrocytes in the CNS; not expressed by target tissues. Promotes survival of a broad range of neurons and enhances differentiation of neurons and astrocytes. Initial identification as in vitro survival factor for chick ciliary neurons: R. Adler et al., Science 204, 1434 (1979). Purification from chick eye: G. Barbin et al., J. Neurochem. 43, 1468 (1984); from rat sciatic nerve: M. Manthorpe et al., Brain Res. 367, 282 (1986). Molecular cloning of rat CNTF: K. A. St"ockli et al., Nature 342, 920 (1989); of rabbit CNTF: L.-F. H. Lin et al., Science 246, 1023 (1989); of human CNTF: A. Lam et al., Gene 102, 271 (1991); A. Negro et al., Eur. J. Biochem. 201, 289 (1991). Effect on motoneuron survival and proposed role as a “lesion factor” released in pathophysiological conditions: M. Sendtner et al., J. Cell Sci. Suppl. 15, 103 (1991). Review of bioactivity and structural relationship with hematopoietic cytokines: N. Y. Ip, G. D. Yancopoulos, Prog. Growth Factor Res. 4, 139-155 (1992). Review of CNTF receptor: S. Davis, G. D. Yancopoulos, Curr. Opin. Neurobiol. 5, 281-285 (1993). Review: M. Manthorpe et al. in Neurotrophic Factors, S. E. Loughlin, J. H. Fallon, Eds. (Academic Press, San Diego, 1993) pp 443-473.