NGFismainlyresponsibleforthesurvivalandthedifferentiationandthefunctionalactivitiesofsensoryandsympatheticneuronsintheperipheralnervoussystem.Italsoplaysanimportantroleinthedevelopmentandfunctionalactivitiesofcholinergicneuronsinthecentralnervoussystem.SinceNGFissynthesizedalsoinnon-neuronaltissuesitmayhaveamuchwiderspectrumofbiologicalactivitiesthanthoughtpreviously.NGFstimulateschemotacticmigrationofhumanpolymorphonuclearleukocytesinvitro.NGFstimulatesthegrowthanddifferentiationofBcellsandthegrowthofTcellsandofsometumorcelltypes.NGFinhibitsimmunoglobulinproductionbyvarioushumanplasmacell.ThecytokinesIL-1,IL-6,andbFGFarepotentinducersofNGF.NGFinducesthesynthesisofIL-1inpheochromocytomacellswhichinturnactsasagrowthfactorforglialcellsandinducesthesynthesisofNGFfollowingnerveinjuries.InthymicstromalcellsNGFinducesthesynthesisofIL-6.NGFinducesthesynthesisofthefosoncogeneandthemyconcogeneandalsoinfluencestheexpressionofEGF.OnereceptorthatisresponsibleformediatingmostoftheactivitiesofNGFisexpressedpreferentiallyinneuronaltissues.Theproductofthetrkgene,NGFexpressedinhuman293cellsisanon-disulfidebondedhomodimericproteinwithanapparentmolecularmassof13kDa.Itpossessesanintrinsictyrosine-specificproteinkinaseinitsintracellulardomain.