May participate in the energy homeostasis regulation. First detected at the anterior position of the embryo at the first somite stage. From the late segmentation and pharyngula periods, expressed in a region ventral to the forebrain, and in the midbrain, hindbrain, and spinal cord. Expressed in the prospective extraocular muscles, mesencephalic neurons residing along the tract of the posterior commissure and interneurons in the spinal cord. Belongs to the NK-1 homeobox family.