DKK4 and hepatoblastoma: Cross-referencing the significantly up-regulated gene set against the 20 most up-regulated hepatoblastoma genes reported by Sumazin et al (5), we found 14 matches: DKK1, GPC3, HMGA2, REG3A, DLK1, COL2A1, DKK4, TNFRSF19, NPNT, CDCA7, SLC7A11, SERPINI1, AFP and LIN28B. A similar comparison with a 16 gene hepatoblastoma classifier reported by Cairo et al (15), yielded 12 genes with concordant expression patterns as in the C2 group (more aggressive one): GHR, APCS, ALDH2, C1S, CYP2E1, APOC4, HPD, RPL10A, BUB1, IGSF1, AFP and DUSP9.