Transcription factor that may play a central role in activating or maintaining gene expression in the vegetal pole. Part of a gene regulatory circuit with Erg and Tgif that operates early in mesoderm development. At the blastula stage, expressed within the vegetal pole domain and throughout the cells fated to become the endomesoderm. By mid-gastrula, expressed throughout the archenteron, with some clearing evident at the tip of the mesodermal bulb. Expressed at the larvae spines.