In keeping with a restricted expression of RARγ within primitive cells, the binding sites for RAR/RXR dimers within undifferentiated F9 embryonal carcinoma cells coincided with loci that are targeted by transcription factors that are important to pluripotency (SOX2, NANOG, and POU5f1) (Chatagnon et al., 2015). Here, POU5F1 is linked to embryonal carcinoma.