May play a pivotal role in the transcriptional cascade that specifies primary neurons in embryos. Stabilizes the higher neural potential of selected progenitor cells that express neurog2/X-ngnr-1 by maintaining Delta-Notch signaling. Thus ensures the transition between neural competence and irreversible commitment to a neural fate. Also promotes neuronal differentiation by activating neurod1 expression, directly or indirectly. In embryos, expressed in precursors of primary neurons. In adults, expressed at high levels in the brain, and at low levels in the somatic muscles, testis, and possibly the spleen. Expression begins during primary neurogenesis at the neural plate stage (stage 12) and accumulates at the tailbud stage. Expressed after neurog2/X-ngnr-1 and before neurod1. Also expressed in adults. Belongs to the COE family.