Transcriptional repressor of genes that require a bHLH protein for their transcription (By similarity). May serve as a transcriptional regulator of the Achaete-scute complex (AS-C) genes (PubMed:1528887). Contributes to the neural-epidermal lineage decision during early neurogenesis (PubMed:1427040). Part of the Notch signaling pathway (PubMed:1427040). Transcription repression requires formation of a complex with a corepressor protein (Groucho). In larvae, detected in neuroblasts (at protein level) (PubMed:22357926). In imaginal disks, expressed as follows: in the eye disk, within and posterior to the morphogenetic furrow; in the wing pouch, in the presumptive intervein regions and wing margin; in the leg disk, general expression (PubMed:1427040). Has a particular type of basic domain (presence of a helix-interrupting proline) that binds to the N-box (CACNAG), rather than the canonical E-box (CANNTG). The C-terminal WRPW motif is a transcriptional repression domain necessary for the interaction with Groucho, a transcriptional corepressor recruited to specific target DNA by Hairy-related proteins.