PTK2 and glioblastoma: The role of hypoxia and invasion in GBM has been largely explored in literature, and this correlation was attributed to ECM degradation by many factors: (i) acidification of the extracellular milieu; (ii) upregulation of carbonic anhydrase; (iii) EGFRvIII/Integrins/FAK/SRC signaling; and iv) collagen crosslinking by procollagen lysine 2-oxoglutarate 5-dioxygenase upregulation [91,92].