TP53 and glioma: On the other hand, all the patient-derived GBM cells and two of the isogenic high-grade glioma cell lines used in our study, U-251 and SF188, harbor mutations in the TP53 gene [10,34], and all the ATRX-deficient cell lines tested were sensitive to RTKi and PDGFRi irrespective of their TP53 status.