Sequence-specific transcription factor which is part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. Acts on the anterior body structures. Is first detected at the end of the late streak stage in presumptive lateral and extraembryonic mesoderm. During early neurogenesis, it is detected solely in lateral mesoderm. By late neurogenesis and through mid-gestation, it is found in a restricted region of presumed trunk neural crest and the dermatome. Belongs to the Antp homeobox family. Labial subfamily.