TP53 and glioblastoma: To confirm that downregulation of EGFR mediates p53-induced senescence in vivo, we inoculated U87 glioblastoma cells that express doxycycline-inducible EGFR (U87 pLVX-TRE 3G-EGFR) into the right striatum of mouse brains (n = 5– 7 per group).