USP7 and medulloblastoma: When comparing the genetic vulnerability of PPM1D, MDM2, MDM4 and USP7 in neuroblastoma and medulloblastoma cell lines to all the other cancer cell lines in the CRISPR Avana dataset, PPM1D showed strong selective dependency in both neuroblastoma and medulloblastoma (Figure 2E), highlighting the essentiality of intact p53.