Upon differentiation, Oct4 expression remained high when compared with the other two pluripotent-related genes, suggesting that ES-cancer hybrids retained vestiges of a ‘stemness state' (Figure 3c), consistent with the previous report that Oct4 was involved in the expression pattern of ‘cancer stem cells' and its expression is correlated with advanced tumor grade.35 Tissue-specific genes were also examined, including the hepatic marker Alb, the melanin marker tyrosinase and ectoderm and mesoderm markers by RT-PCR. This evidence concerns the gene POU5F1 and neoplasm.