Ciliary neurotrophic factor (CNTF) is a neurotrophic factor that belongs to the four-helix bundle cytokine family and is structurally related to interleukin 6 (IL-6), interleukin 11 (IL-11), leukemia inhibitory factor (LIF), and oncostatin M (OSM). CNTF binds to its receptor CNFTRα and induces formation of a heterodimer of the signal transducing IL-6 receptor gp130 and LIF receptor (LIFR)-β, which triggers JAK/STAT, ERK, and PI3K signaling cascades (Schuster et al.). CNTF plays an important role in neurogenesis and the differentiation of neural stem cells and has been suggested to possess a therapeutic role in treating neurological disorders (Ding et al.; Oppenheim et al.). CNTF has also been shown to protect rod photoreceptors from light-induced damage and have therapeutic effects on retinal degenerative diseases caused by genetic defect or damage induced by toxins, autoantibodies, or strong light (Pernet et al.; Rhee et al.). Another therapeutic role of CNTF has been reported in protecting oligodendrocytes from death induced by apoptosis (Louis et al.). Additionally, CNTF is commonly used to differentiate human pluripotent stem cell (hPSC)-derived neural progenitor cells into astrocytes (Krencik & Zhang). This product is animal component-free.