The Trk (tropomyosin-receptor-kinase) proto-oncogene family of receptor tyrosine kinases contains four members, TrkA, TrkB, TrkC, and TrkE, which are variably expressed throughout the central and peripheral nervous systems. TrkB is the high-affinity to the binding brain-derived neurotrophic factor (BDNF) receptor and neurotrophin-4/5 NT-4/5). TrkB is autophosphorylated on five cytoplasmic tyrosines. The binding of BDNF to TrkB receptor causes many intercellular cascades to be activated such as promoting survival of sensory neurons mainly through Shc site-independent pathways.The signaling activity of these receptors includes the Ras 鈥