POU5F1 and teratoma: However, although OCT3/4 may have a contributory role on its own by downregulating pluripotency signatures [148], this was not fully supported by validation studies (with no difference in staining patterns between sensitive and resistant GCTs), and, also, because other subtypes than teratoma (choriocarcinoma and yolk sac tumor) are negative for this marker and still respond to cisplatin-based treatment [159].