On the contrary, this gene is expressed not only in ESCs but also in several malignancies.58 For example, reactivation of Oct4 is associated with tumor initiation in breast cancer cells59 as well as in poorly differentiated epithelial ovarian cancers.60 Exogenous delivery of specific cDNA combinations reactivates the endogenous Oct4 promoter. The gene discussed is POU5F1; the disease is neoplasm.