TP53 and glioblastoma: As it did not appear that NSC-154829 was acting selectively through the P-Akt pathway, we next studied the p53 pathway which is also frequently mutated in glioblastomas, particularly in "secondary" glioblastomas, which develop from low grade astrocytomas (WHO grade II) to anaplastic astrocytomas (WHO grade III) and finally to glioblastomas (WHO grade IV) [27].