Sequence-specific transcription factor which is part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. First expressed at 14 hours post-fertilization (hpf) in the dorsal pre-somitic mesoderm and neural keel at posterior levels, extending into the ventral somitic mesoderm during budding. At 22-26 hpf, expression decreases in the lateral and ventral mesoderm, but is maintained in the neural rod. Expression decreases from posterior to anterior with an anterior expression limit at somite 17. Also expressed in the developing hindgut, except in the most distal portion. At 24-26 hpf, posterior expression begin to weaken and is undetectable by 40-56 hpf. Belongs to the Abd-B homeobox family.