Required for oligodendrocyte and motor neuron specification in the spinal cord, as well as for the development of somatic motor neurons in the hindbrain (PubMed:11955448, PubMed:12121626, PubMed:16908628). Functions together with ZNF488 to promote oligodendrocyte differentiation (PubMed:16908628). Cooperates with OLIG1 to establish the pMN domain of the embryonic neural tube (PubMed:11955448, PubMed:12121626). Antagonist of V2 interneuron and of NKX2-2-induced V3 interneuron development (PubMed:11955448, PubMed:12121626). Interacts with NKX2-2 (PubMed:14573534). Interacts with ZNF488 (PubMed:16908628). The NLS contained in the bHLH domain could be masked in the native form and translocation to the nucleus could be mediated by interaction either with class E bHLH partner protein or with NKX2-2. Expressed specifically in the brain. Expressed in the ventral spinal cord as early as 9.5 dpc. Expression becomes progressively restricted to a narrow zone within the ventral neuroepithelium of the spinal cord. In the 14.5 dpc spinal cord, expressed in the oligodendrocyte progenitors of the ventral ventricular zone, but not dorsal root ganglia Schwann cells. Also expressed scattered in the mantle zone, likely corresponding to oligodendrocyte progenitors migrating out from their site of origin. In the brain, from 10.5 through 14.5 dpc, expressed in numerous cells in the ventricular and subventricular zones of the lateral and medial ganglionic eminences, suggesting that expression might not be limited to the oligodendrocytic lineage. By 15.5 dpc, dispersed throughout the gray matter, with little or no residual expression in the ventricular zone. In the postnatal brain, present preferentially in the white matter, such as corpus callosum and cerebellar medulla. Expressed in the 13.5 and 14.5 dpc retina and in the olfactory epithelium from 11.5 dpc onward. By SHH. Also induced by NKX6-1 in the developing spinal cord, but not in the rostral hindbrain. The bHLH is essential for interaction with NKX2-2.