Transcription factor (By similarity). Involved in the control of early morphogenesis of the intestine, hypodermis and body-wall muscle (PubMed:15066124, PubMed:15102704). Involved in regulating expression of vab-7 (PubMed:15102704). Appears to have partially redundant function to tbx-8 (PubMed:15066124). Positively modulates expression of homeobox protein lin-39, perhaps by binding to regulatory regions of the lin-39 gene, acting in the vulval lineage. Expressed during morphogenesis in the hypodermis, body-wall muscle, intestine and dorsal, lateral and ventral hypodermal cells (PubMed:15066124, PubMed:15102704). First detected in the E cell at the 8 cell stage and its daughter Ea and Ep cells until the 24 cell stage (PubMed:15066124, PubMed:15102704). At the 24 cell stage detected in 5 cells including AB descendant cells and also the Ca and Cp cells (PubMed:15066124). At the 200 cell stage, detected in two pairs of MS descendant cells (PubMed:15066124). Thereafter detected in a subset of cells at each stage up to approximately the 400 cell stage, becoming undetectable just before morphogenesis (PubMed:15066124). During morphogenesis detected in the hypodermis, body-wall muscle, intestine and dorsal, lateral and ventral hypodermal cells up until early L1 larval stage (PubMed:15066124, PubMed:15102704). RNAi-mediated knockdown causes about 5% embryonic lethality with 1-10% of hatching larvae displaying posterior morphological defects (PubMed:15892873, PubMed:15102704). Defective intercalation of dorsal hypodermis (PubMed:15102704). Simultaneous RNAi-mediated knockdown of tbx-8 causes at least 48% of embryos to fail to hatch and those that do display severe morphological defects and die as larvae (PubMed:15892873, PubMed:15102704). Simultaneous RNAi-mediated knockdown of tbx-8 abolishes muscle expression of vab-7 (PubMed:15102704). RNAi-mediated knockdown at the larval L1 stage causes a decrease in expression of lin-39 at the larval L3 stage (PubMed:24885717). Knockdown in L1 stage larvae, in a lin-39 mutant background, causes abnormal fusion of vulval precursor cells at larval stage L2 (PubMed:24885717).