Appears to be involved in the regional specification of the anterior head of Xenopus embryos. Initially expressed in the anterior dorsal region of early embryos and later exclusively in the primordium of the anterior pituitary gland. Activated during the early gastrula stage of embryogenesis. Expression is weak between stages 10 and 11 then increases sharply between stages 11 and 12, peaking at stage 13 and then sharply declining. Undetectable after stage 35. By Ammonium chloride. Belongs to the ANF homeobox family.