NGF and neuroblastoma: Neurotrophins and their cognate receptors, belonging to the tropomyosin-related kinase family of RTKs, have central roles in the development and maintenance of the nervous system, and neuroblastoma cells expressing tropomyosin-related kinase A (TrkA) have been shown to undergo differentiation in response to stimulation by its high-affinity ligand, nerve growth factor (NGF).