Ciliary Neurotrophic Factor (CNTF) is a common extracellular polypeptide hormone who has neuroprotective effects on a variety of central and also peripheral nervous system neurons. It promotes differentiation and maturation of oligodendrocyte precursor cells to oligodendrocytes under in vitro conditions and thus improves remyelination. In addition, CNTF can also increase the survival of mature oligodendrocytes. To test the effect of CNTF on cell proliferation of SK-N-SH , SK-N-SH cells were seeded into triplicate wells of 96-well plates at a density of 5, 000 cells/well and allowed to attach overnight, then the medium was replaced with serum-free standard DMEM  prior to the addition of various concentrations of CNTF. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 µl of CCK-8 solution was added to each well of the plate，then measure the absorbance at 450 nm using a microplate reader after incubating the plate for 1-4 hours at 37 °C .Cell proliferation of SK-N-SH cells after incubation with CNTF for 72h observed by inverted microscope was shown in Figure 1.

The dose-effect curve of CNTF was shown in Figure2. It was obvious that CNTF significantly promoted cell proliferation of SK-N-SH cells. The ED50 for this effect is typically 4.685-83.37ng/ml.