Synonyms:FOX3,HRNBP3, NeuN, RBFOX3 Background:NeuN(Hexaribonucleotide Binding Protein-3), a homologue to sex-determining genes in Caenorhabditis elegans, is a neuronal nuclear antigen that is commonly used as a biomarker for neurons.Anti-NeuN has been used widely as a reliable tool to detect most postmitotic neuronal cell types. The immunohistochemical staining is primarily localized in the nucleus of the neurons with lighter staining in the cytoplasm.