Similarly, chlorpyrifos and parathion treatment in young rats was reported to decrease neurotrophic factors, such as NGF and brain-derived neurotrophic factor, in the hippocampus and cerebral cortex.39 NGF-mediated neuroprotection via the TrkA receptor enhances neurite outgrowth in human neuroblastoma cells, which is blocked by organophosphate drugs.40 Unfavorable environmental conditions surrounding neuronal cells may promote neuronal cell death. The gene discussed is NGF; the disease is neuroblastoma.