DDX1 and neuroblastoma: In turn, shRNA-mediated DDX1 knockdown in neuroblastoma cells with a DDX1-MYCN coamplification resulted in reduced rapamycin sensitivity (Fig. 6C; Supplementary Fig. S9G), indicating that high DDX1 expression was required for mTOR inhibitor sensitivity in the context of DDX1-MYCN coamplification.