Probable transcription factor needed for the proper production of touch cell precursors (PubMed:11333230). Involved in specification of lateral neuroblasts (PubMed:28716930). Essential for embryonic morphogenesis (PubMed:11333230). Expressed in the ectodermal cells of embryos and seam cells and ventral cord motor neurons of young larvae. Expressed from the twofold embryo stage through to L4 larval stage (PubMed:11333230). Expressed in the embryonic mother cell of Q and V5 neuroblasts, AB.p(lr)apapaa, and abolished in V5 neuroblasts after division but maintained in Q cells until they divide (PubMed:28716930). Expressed in P-neuroblasts before hatching, maintained while P nuclei migrate into the ventral midline in early L1-stage larvae, and declines after P-neuroblasts divide (PubMed:28716930). Worms exhibit the absence of AVM, PVM, and PLM touch cells, defective egg laying, embryonic or larval lethality, cell degeneration, malformation of the posterior body, and uncoordinated movement. Belongs to the Msh homeobox family.