When fusion was conducted between cells of the same species e.g. mouse F9 embryonal carcinoma (EC) cells and mouse Oct4-GFP transgenic neural stem cells (NSCs), the induction of the pluripotency marker OCT4-GFP was observed within 24 hours of fusion, suggesting that reprogramming occurred in one cell cycle and that a single round of DNA replication was sufficient [13]. Here, POU5F1 is linked to embryonal carcinoma.