HMGA1 and teratoma: For instance, high mobility group proteins HMGA1 and HMGA2 are nuclear proteins that are expressed differently with respect to the state of differentiation of the testicular germ cell tumor.[14] Over-expression of HMGA1/2 has been reported in pluoripotent embryonal carcinoma, whereas loss of HMGA1 expression has been reported in yolk sac tumor, and that loss of HMGA1/2 expression has been shown in mature adult tissue of teratoma areas.