Probable transcription factor, acting as a progenitor identity factor regulating the development of lineally-related embryonic cells including glial, excretory and neuronal cells (PubMed:25738873, PubMed:21041366). Mediates chemosensory function of ASE and AWC neurons (PubMed:14536063, PubMed:15095973). In ASE neurons, required to diversify the fate of the ASEL neurons from the ASER neurons (PubMed:14536063, PubMed:15095973). Acts cell-autonomously to establish a neuronal left right asymmetry, possibly promoting asymmetric expression of the helix-loop-helix proteins ngn-1 and hlh-2 (PubMed:21041366). In cooperation with the transcription factor sox-2, required for the differentiation of AWC olfactory neurons (PubMed:26341465, PubMed:15095973). May regulate the expression of sox-2 in AWC olfactory neurons (PubMed:26341465). Interacts with sox-2. Expressed in ASE and AWC chemosensory neurons (PubMed:14536063, PubMed:15095973). Expressed left-right asymmetrically in the embryo, in the grandmother cell and the mother cell to the MI pharyngeal motorneuron but in neither analogous precursors of the e3D neuron (PubMed:21041366). Up to the comma stage, expressed in six lineages that produce diverse cell types including pharyngeal cells, muscles, neurons and glia. Belongs to the paired homeobox family.