Transcriptional regulator which binds to DNA to regulate gene expression and promote seam cell development and differentiation during embryogenesis (PubMed:15659483, PubMed:19607822). Plays a role in maintaining the boundaries between the lateral rows of seam cells and the ventral and dorsal row of epidermal cells during embryonic development (PubMed:15659483). Negatively regulates the expression of the fusion effector protein eff-1 to prevent seam cell fusion with the dorsal and ventral epidermal cells during embryonic elongation (PubMed:15659483). Positively regulates seam cell self-renewal and expansion during the L2 larval stage to promote seam cell development (PubMed:19607822). This role does not seem to be via regulation of eff-1 expression (PubMed:19607822). Specifically, it is required for the asymmetric division of the V5.p seam cell during the L2 larval stage, and in turn the asymmetric nuclear distribution of pop-1 in V5.p daughter cells (PubMed:19607822). Expressed in seam cells. Expressed throughout embryonic development (PubMed:15659483). In embryos, highly expressed after the first cleavage until the early 3-fold stage in one bilateral row of epidermal hyp5, H0-H2, V1-V6 and T-cells (the seam cells) (PubMed:15659483). In later embryonic stages, expressed in anterior neurons and in the DA1 and DD1 motorneurons after hatching (PubMed:15659483). Expressed in seam cells at all larval and adult stages (PubMed:19607822). In dividing seam cells at the L2 larval stage, expressed equally in both daughters and expression in the anterior daughter ceases when it fuses with hyp7 (PubMed:19607822). Embryonic lethality due to embryos with disorganized epidermal cells, which cause morphological and elongation defects (PubMed:15659483). The seam cells in these embryos abnormally fuse to the syncytial hypodermis during embryonic elongation and ectopically express eff-1 (PubMed:15659483). RNAi-mediated knockdown results in embryonic lethality and embryos exhibit seam cell differentiation defects as indicated by a decrease in expression of early seam cell proteins including elt-5, nhr-73 and nhr-74 (PubMed:15659483). Belongs to the engrailed homeobox family.