MDM2 and neuroblastoma: We examined the effect of MX25-1 (Figure 1A) on expression of MYCN as well as MDM2 in two MYCN-amplified NB cell lines NB-1643 (wt-p53) and LA1-55N (p53-null) and found that MX25-1 inhibited the expression of both proteins (Figure 1B).