Transcriptional regulator. Involved in the initiation of neuronal differentiation. Activates transcription by binding to the E box-containing promoter (By similarity). Efficient DNA binding requires dimerization with another bHLH protein. Forms homo- or heterooligomers with myogenin, E12 and ITF2 proteins (By similarity). Abundantly expressed during development of the central nervous system, in particular in proliferating neuroblasts and in cells at the initial stages of differentiation. Also expressed at high levels in morphogenetically active regions such as limb buds, somites and mesonephric tubules. Expression decreases once cellular differentiation is over.