Particularly, a comprehensive analysis of a GBM patient-derived xenograft model, which integrated mass spectrometry imaging, histology, magnetic resonance imaging, phosphoproteomics, and mRNA sequencing, showed that the distribution of the EGFR inhibitor erlotinib within intracranial tumors was insufficient to inhibit EGFR tyrosine kinase signaling, despite its promising in vitro efficacy [94]. Here, EGFR is linked to glioblastoma.