Sema3A binding to Neuropilin-1:Plexin-A complex results in conformational change of plexin-A and this conformational change permits Fes nonreceptor tyrosine kinase to bind and phosphorylate Plexin-A. The specific tyrosine residues phosphorylated in the cytoplasmic domain of plexins in response to semaphorin stimulation have not yet been identified.