NANOG and neoplasm: Although tumor heterogeneity composed of tumor stem cells and differentiated tumor cells is produced by tumor stem cell function, the TS cells derived from Huh7 and SNU449 HCC cells and patient-derived cells from hepatocellular carcinoma had similar mechanism in the maintenance of stemness by upregulation of complement proteins C7 and CFH, and through NANOG, OCT4, SOX2, and c-Myc expression15.