Transcription factor that binds to the promoter of target genes (PubMed:20150279). Regulates fate specification and/or differentiation of multiple cell types arising from the embryonic mesodermal (M) lineage and the ABp(l/r)paa precursors (PubMed:20150279, PubMed:16107479). In the postembryonic M lineage, regulates cleavage orientation, cell proliferation and cell fate specification (PubMed:16107479). Regulates hlh-1 expression to specify coelomocyte fate in the mesodermal (M) lineage (PubMed:16107479). In AWC neurons, initiates expression of ceh-36, leading to the expression of terminal differentiation genes (PubMed:20150279). Regulates ventral cephalic sheath (CEPsh) glia differentiation and expression of transcription factor hlh-17 in CEPsh glia (PubMed:18508862). Promotes terminal differentiation and morphogenesis of the epithelial duct and pore cells (PubMed:22537498). In the duct cell, cooperates with the EGF-Ras-ERK pathway in turning on the terminal differentiation gene lin-48 (PubMed:22537498). Expressed in a subset of head neurons, including AIM and ASK (at protein level). First expressed around the 50-cell stage of embryogenesis in proliferating cells that are primarily located at the anterior of the embryo in the early M lineage (at protein level) (PubMed:16107479, PubMed:18316179, PubMed:22537498). During morphogenesis, expression becomes restricted to a small subset of head neuronal precursors, including AIM and ASK (at protein level) (PubMed:16107479, PubMed:18316179). Expressed in precursor cells of the left and right ventral CEPsh glia, ABplpaaapap and ABprpaaapap, respectively and also in precursors of dorsal CEPsh glia (PubMed:18508862). Expressed in the duct and pore lineages, persisting through the stages of ventral enclosure and 1.5-folds of embryonic development, but not detectable by the L1 larval stage, when duct and pore cells achieve mature morphology (PubMed:22537498, PubMed:25738873). Expressed in ABpxp descendants that give rise to the excretory system (PubMed:25738873). Transiently expressed in AWC neurons in L1 larvae until abolished shortly after hatching (PubMed:20150279). During the L2 and L3 larval stages, expressed in a group of proliferating cells surrounding the gonad (PubMed:18316179). Belongs to the HMX homeobox family.