Probable transcription factor that is required for initial outgrowth and pathfinding of axon growth cones along the ventral nerve cord (VNC) (PubMed:9216999, PubMed:11222641). Involved in specifying neuron identity, perhaps in concert with nuclear hormone receptor family member fax-1 (PubMed:10207148, PubMed:16183052). Plays a role in locomotion and mechanosensory response, perhaps via regulation of chemosensory receptor expression, and is required for expression of glutamate receptors, including glr-1, glr-4 and glr-5 (PubMed:10207148, PubMed:11222641). Expressed in neurons from 260 minutes of embryogenesis, comma stage and into adulthood (at protein level) (PubMed:10207148). Expressed in late stage (3 and a half-fold) embryos in at least 20 pairs of neurons of the head, including the AVA, AVD and AVE interneurons, ASH sensory neurons, and RMD and SMB motor neurons (PubMed:10207148). Expressed at high levels in the AIN, AVH, AVJ, AVK, RIV, SAA and SIB interneurons (PubMed:10207148). At larval L2 stage, expressed in the tail in the PVT neuron (PubMed:10207148). Belongs to the paired homeobox family.