Two distinct but related NANOG proteins may be active in CSCs, one encoded by NANOG and the other by NANOGP8, which is transcriptionally active as a retrogene in several types of cancer cells (Zhang et al. 2006; Jeter et al. 2009, 2011; Zbinden et al. 2010; Ambady et al. 2010; Eberle et al., 2010; Zhang et al. 2010, Ma et al. 2011, 2012; Ishiguro et al. 2012; Uchino et al. 2012; Ibrahim et al. 2012). Here, NANOG is linked to cancer.