POU5F1 and teratocarcinoma: We have previously shown that ectopic Oct4 induction in this line at somitogenesis stages leads to reactivation of the pluripotency indicator Nanog within 24 h (hr) after explantation in EpiSC culture conditions and subsequent re-establishment of pluripotency evidenced by the derivation of stable EpiSC lines and formation of teratocarcinomas from grafts of tissue pieces to the adult kidney capsule [3].