NANOG and embryonal carcinoma: It has been reported that abnormal expression of Nanog is associated with human germ cells and several other types of cancers, such as gliomas [6], embryonic carcinomas [7], prostate cancers [8], breast cancers [9], etc. Down regulation of Nanog inhibits the proliferation, colony expansion and clonogenic growth of tumor cells [10], while over expression of Nanog may induce chemoresistance in breast cancer and prostatic cancers [11].