SOX2 is best known as a core pluripotency factor, maintaining the undifferentiated phenotype of pluripotent stem cells, and is closely co-regulated alongside core pluripotency factors OCT4 and NANOG in undifferentiated embryonic stem cells (ESCs), embryonal carcinoma cells (ECCs) and induced pluripotent stem cells (iPSCs) [8, 13, 14]. This evidence concerns the gene SOX2 and embryonal carcinoma.