Sequence-specific transcription factor which is part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. Expressed in the developing limb buds. Expressed in the posterior-most regions of the fetus. Strongly expressed in 12.5 day old fetuses in both spinal cord and pre-vertebral column with an anterior boundary of expression lying at the level of the second or third lumbar pre-vertebrae. Belongs to the Abd-B homeobox family.