MDM2 and neuroblastoma: The concentration of RG7388 required to inhibit growth by 50% (GI50) was determined using XTT cell proliferation assays in a panel of neuroblastoma cell lines, including 5 p53 mutant and 16 p53 wt cell lines of varying MYCN, MDM2 and p14ARF status, together with the p53 wt MYCN− regulatable SHEP Tet21N cells (Table 1, Figure 1A, Supplementary Figure 1A).