The most differentially overexpressed gene with promoter hypomethylation in clusters E1/E2 was NQO1. The differential methylation status of the NQO1 promoter between cluster F and clusters E1/E2 was very similar to that observed between normal adult and fetal livers (Supplementary Fig. 10, a), which suggested that tumor differentiation highly affected NQO1 promoter methylation in hepatoblastoma. Here, NQO1 is linked to neoplasm.