Immunohistochemical studies revealed that AFPs were diffusively distributed in both yolk sac tumor components, that the embryonal carcinoma component [Fig. 3A], OCT3/4 was positive in embryonal carcinoma component [Fig. 3B], and that AE1/AE3 was positive in glandular areas. The gene discussed is SLC4A1; the disease is embryonal carcinoma.