CNTF is a potent neural factor that was originally characterized as a vital factor for the survival of chick ciliary neurons in vitro. CNTF is also important for the survival of other neural cell types including primary sensory neurons, motor neurons, basal forebrain neurons and type 2 astrocytes. CNTF is highly conserved across species and exhibits cross-species bioactivity. Recombinant rat CNTF is synthesized as a 199 amino acid polypeptide (22.7 kDa) lacking a hydrophobic N-terminal signal for secretion.