Transcriptional repressor which maintains cell fate asymmetry of AWC neurons in adults by repressing the expression of multiple AWC (OFF) genes, including srsx-3 in the AWC (ON) neuron. Expressed in both AWC neurons (PubMed:20713521). Also expressed in the FLP mechanosensory neurons (PubMed:20713521). RNAi-mediated knockdown has little effect on srsx-3 expression in the AWC neuron. Belongs to the HMBOX1 homeobox family.