Probable transcription factor required for differentiation and migration of neuronal cells, such as RID and CAN neurons (PubMed:2361334, PubMed:15282156). Specifically, plays a role in the terminal differentiation of RID peptidergic neurons (PubMed:27855782). Also required for CAN neuron axon guidance (PubMed:15282156). Expressed in muscles and neurons from embryogenesis to adulthood (PubMed:15282156, PubMed:27855782). First expressed post-fertilization, then accumulates in anterior cells of the embryo that give rise to neuronal and mesodermal tissues and body wall muscle cells, where expression persists and increases (PubMed:15282156). Also expressed in posterior nuclei post-fertilization (PubMed:15282156). At the 2-fold stage of embryogenesis, expression is restricted to fewer cells (PubMed:15282156). RNAi-mediated knockdown results in 60% larval lethality (PubMed:15282156). Surviving animals display uncoordinated locomotion, withered tail morphology, and defects in both CAN neuronal cell migration and axon guidance (PubMed:15282156). Belongs to the SIX/Sine oculis homeobox family.