Plays an essential role in the maturation of presomitic mesoderm cells by individual attenuation of both FGF and WNT signaling. Expressed at 5.5 dpc in the distal visceral endoderm. Expression increases at 6.5 dpc in the most anterior part of the visceral endoderm. At 7.0 dpc expression spreads over the anterior visceral endoderm and occurs in the anterior ectoderm. At 7.75 dpc expressed in the definitive anterior endoderm, anterior mesoderm and anterior neuroectoderm. At 8.25 dpc, when the headfold is formed, expressed in the forebrain, foregut and in segmented somites. At 12.5 dpc, expressed in cerebrum cortex, lateral ganglionic eminences, preoptic area neuroepithelium, hypothalamus, ventral part of otic placode including adjacent mesenchyme, a part of the tongue, endocardial cushion around aortic valve, myotome and muscle primordia. Mice exhibit no defects in head development. Mice are live-born. About one-third of the homozygous mutants were normal and fertile and about two-thirds were dwarf. Reduction in weight gain became apparent at the postnatal third week; about half of the dwarf mice subsequently resumed the weight increase, although they remained dwarf; the other died within a month after birth. Belongs to the shisa family.