Medulloblastoma (MB) is the most common malignant brain tumor in children. Although treatments like surgery, chemotherapy, and radiation can control the disease, they often come with serious long-term side effects. For children whose tumors carry a mutation in the p53 gene—a gene that normally helps prevent cancer—treatment is even more difficult. These p53-mutant tumors are more likely to return after therapy, and there are currently no effective treatments for relapse. One promising idea is to force cancer cells to enter a state called senescence, where they stop growing but don’t die. Senescent cells are also more likely to attract the immune system’s attention, making them easier to eliminate. However, when p53 is mutated, this natural process doesn’t happen effectively. Scientists are now exploring ways to trigger senescence through other methods, even when p53 is not working. One such approach involves blocking a protein called PP2A, which has shown the ability to induce senescence and improve immune response in mouse models of MB. This opens the door to new combination therapies that use both senescence-inducing drugs and immunotherapy.