Background The Ras/Raf/ERK1/2 signaling pathway controls many cellular responses such as cell proliferation,migration,differentiation,and death.In the nervous system,emerging evidence also points to a death-promoting role for ERK1/2 in both in vitro and in vivo models of neuronal death.To further investigate how Ras/Raf/ERK1/2 up-regulation may lead to the development of spinal cord injury,we developed a cellular model of Raf/ERK up-regulation by overexpressing c-Raf in cultured spinal cord neurons (SCNs) and dorsal root ganglions (DRGs).Methods DRGs and SCNs were prepared from C57BL/6J mouse pups.DRGs or SCNs were infected with Ad-Raf-1 or Ad-Null adenovirus alone.Cell adhesion assay and cell migration assay were investigated,Dil labeling was employed to examine the effect of the up-regulation of Ras/Raf/ERK1/2 signaling on the dendritic formation of spinal neurons.We used the TO-PRO-3 staining to examine the apoptotic effect of c-Raf on DRGs or SCNs.The effect on the synapse formation of neurons was measured by using immunofluorescence.Results We found that Raf/ERK up-regulation stimulates the migration of both SCNs and DRGs,and impairs the formation of excitatory synapses in SCNs.In addition,we found that Raf/ERK up-regulation inhibits the development of mature dendritic spines in SCNs.Investigating the possible mechanisms through which Raf/ERK up-regulation affects the excitatory synapse formation and dendritic spine development,we discovered that Raf/ERK up-regulation suppresses the development and maturation of SCNs.Conclusion The up-regulation of the Raf/ERK signaling pathway may contribute to the pathogenesis of spinal cord injury through both its impairment of the SCN development and causing neural circuit imbalances.