Moreover, many similar tumor genes and pluripotency factors; nanog homeobox (nanog), POU domain, class 5, transcription factor 1 (oct4/pou5f1), SRY-box containing gene 2 (sox2) and Krüppel-like factor 4b (klf4), have a conserved expression pattern in zebrafish and humans [22,23] and similar methylation patterns have been also obtained [24]. This evidence concerns the gene POU5F1 and neoplasm.