SMAD9 and neuroblastoma: The common downregulated genes were subjected to PPI analysis to further identify the downregulated hub genes, and we found that AURKA-linked cell cycle and mitotic nuclear division genes such as AURKA, AURKB and CCNA2 might play a pivotal role in SMAD9-MYCN-mediated malignancy (Fig. 7E), which was validated by performing Q-RT-PCR analysis of NB cells (Fig. 7F) and tissues from SCH (Fig. 7G).