Probable transcription factor involved in postembryonic differentiation of the ALA neuron, and regulation of genes that contribute to behavioral quiescence, a sleep-like behavior mediated by ALA (PubMed:20501595). Regulates its own expression and also that of homeodomain ceh-14, together forming an autoregulatory loop in the ALA neuron (PubMed:20501595). Involved in fasciculation-independent longitudinal axonal navigation in many neurons (PubMed:10887091). Expressed at the L1 larval stage in five neurons of the ring ganglia; a dorsal neuron, ALA, and four ventral SIA neurons (SIADR, SIADL, SIAVR and SIAVL) (at protein level) (PubMed:10887091). Earliest expression is at the end of gastrulation (PubMed:10887091). Expressed at the comma stage, in two dorsal neurons in the head, and in six cells on the ventral side of the head, just anterior to the excretory pore (PubMed:10887091). ALA and SIA axons exhibit outgrowth abnormalities, failing to run along the lateral cord to the tail (PubMed:10887091). ALA axons are shortened further in a vab-8 mutant background (PubMed:10887091). Drastically reduced expression of let-23/EGFR and plc-3/PLCgamma in ALA neurons (PubMed:20501595). RNAi-mediated knockdown causes severe defects in the ALA neuron in young adults (PubMed:20501595). Belongs to the paired homeobox family.