Probably plays a role in patterning events during embryonic limb development. May also be involved in programmed cell death. Early limb development. First present in an asymmetric arc extending from the anterior border of the limb bud to the mesenchymal cells directly adjacent to the AER. Later abundantly expressed in the proximal anterior periphery and in the mid-proximal region of the posterior periphery. In older wing buds, detectable throughout the necrotic mesenchyme between the developing digits. Belongs to the Msh homeobox family.