HMGA1 and yolk sac tumor: In fact, we have reported that HMGA proteins are expressed depending on the differentiation state of TGCTs: in pluripotential embryonal carcinoma cells, HMGA1 and HMGA2 have been reportedly overexpressed, in mature adult tissue of teratoma areas both proteins have not been detected, in seminomas just HMGA1 have been found to be overexpressed, and in yolk sac tumors just HMGA2 [24].