Analysis of the excised tumors revealed an absence of HIF2α immunoreactivity in certain regions, which coincided with high immunoreactivity for the cell cycle marker Ki67 and low TH staining, emphasizing the inverse relationship between high levels of HIF2α and neuroblastoma tumor growth as well as indicating that the suppressive effect of iHIF2a on tumor growth could be underestimated. This evidence concerns the gene MKI67 and neoplasm.