fig3

Figure 3. Molecular pathways associated with TMZ resistance. In the RTK pathway, activation of RTK results in downstream signaling controlling cell survival or apoptosis. Amplification of EGFR and inclusion of the mutant variant EGFRvIII, both RTKs, occurs in a majority of GBM. EGFRvIII has been shown to be a constitutively active mutant of EGFR, with ligand-independent activation resulting in RTK/RAS/PI3 dysregulation. Modified from Pearson et al.^[63]. TMZ: temozolomide; RTKs: receptor tyrosine kinases; EGFR: epidermal growth factor receptor; EGFRvIII: epidermal growth factor receptor variant III