Figure 1.

NTRK downstream signal pathway and function. NTRK has the typical structure of extracellular ligand binding domains, a transmembrane region, and intracellular kinase domain. When NTRK binds with its ligand, the downstream PI3K/MAPK/PLC pathway will be activated and cause cell survival, proliferation, and differentiation. BDNF—brain-derived neurotrophic factor; NT4—neurotrophin 4; NGF—neurotrophin nerve growth factor; NT3—neurotrophin 3; PI3K—Phosphoinositide 3-kinase; MAPK—Mitogen-activated protein kinase; PLC—Phospholipase C.