Addition of either tamoxifen (Tam), which is metabolized to 4-OHT in the liver leading to reactivation of p53, or Dox (suppression of MYCN expression) resulted in loss of clonogenic capacity and reduced growth in GTML/Trp53KI/KI medulloblastoma-derived neurospheres, associated with loss of MYCN expression and induction of p53 target genes, respectively (Figures S3D–S3F). Here, MYCN is linked to medulloblastoma.