MYCN and neuroblastoma: The results of staining for the endothelial cell-specific marker isolectin IB4 showed that there were no significant differences in the number of blood vessels in non-MYCN-amplified NB cell lines or xenograft tumor tissue sections, regardless of treatment with ONC201, whereas ONC201 significantly reduced the number of blood vessels in the SK-N-DZ group (Fig. 5A and B).