Engrailed (en) and invected (inv) are functionally redundant transcription factors in neuronal precursor cell NB5-3 specification. Inv is unable to substitute for en in other regulatory processes such as maintaining gsb expression in the neuroectoderm after stage 10 of embryogenesis. Maintenance of gsb expression in row 5 of the neuroectoderm involves an as yet unidentified short range signaling molecule. Expressed in row 6/7 of the embryonic neuroectoderm. Belongs to the engrailed homeobox family.