KLF4 and cancer: Several factors known to play a central role in embryonic stem cells and used in epigenetic reprogramming, such as pluripotency factors OCT4, NANOG, SOX2 and Klf4, have been reported to be expressed in subpopulations of cancer cells from different tumour types (Hochedlinger et al., 2005; Feinberg et al., 2006; Lengner et al., 2007; Doi et al., 2009; Fischedick et al., 2014; Lu et al., 2014; Marucci et al., 2014; Ohnishi et al., 2014; Xiong et al., 2018).