TP53 and medulloblastoma: Pei et al. and Kawauchi et al. both introduced Myc into murine cerebellar cells by genetic engineering, which, in combination with p53 blockade (either by introducing dominant negative p53 into CD133+ cells of the cerebellar white matter or by using Trp53 null granule neuron precursors) led to the formation of medulloblastomas resembling the Group 3 subtype [25, 26].