NANOG and embryonal carcinoma: Nanog, a homeobox transcription factor, plays a crucial role in the second embryonic cell-fate specification.62 This molecule is required for the maintenance of pluripotency but absent from differentiated cells.63,64 In 2004, Kristian Almstrup and colleagues65 revealed embryonic SC-like features of testicular carcinoma in situ by genome-wide expression profiling: Nanog was upregulated during progression to embryonic carcinoma.