MDM2 and neuroblastoma: p53 activity was initially claimed to be lacking in many NB tumors due to its cytoplasmic localization, while subsequent studies reported that p53 signal transduction is functional in NB cells [48, 49] and that MDM2 antagonists can activate p53-induced apoptotic signaling in NB by inhibiting the p53-MDM2 interaction [50, 51].