Neurotrophins are growth factors that control survival, development and function of neurons in the central and peripheral nervous system. Four mammalian neurotrophins have been described: nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). Neurotrophins can bind members of the tropomyosin-related kinase (TRK) family of receptors as well as p75 neurotrophin receptor p75(NTR).TRKs are tyrosine kinases that are activated by the binding of neurotrophins. Signal transduction involves the recruitment of adapter molecules Shc, GRB2 and GAB1 which in turn activate the Ras/Raf/MEK/ERK pathway and the PI3K/AKT pathway...