NQO1 and hepatoblastoma: In fact, not only was the ODC1 protein level decreased in NQO1-low hepatoblastoma samples compared with NQO1-high samples, despite the comparable high ODC1 mRNA expression (Supplementary Fig. 12, a–c), but we also observed a reduction in ODC1 protein levels in HepG2 cells after NQO1 inhibition (Supplementary Fig. 12, d, e); these results indicate that NQO1 plays an important role in the stabilization of the ODC1 protein in hepatoblastoma cells.