PTEN and glioblastoma: Stabilization/increased HIF1αexpression results from the activation of the PAM pathway throughoverexpression of the EGFR gene and loss of PTEN, resulting in vascularizationof tumors in GBM.543,544 Additionally, integrins activatethe PAM pathway through extracellular matrix (ECM) adhesion, integrin-linkedkinase (ILK) activation, a surge in HIF-1α, and VEGF productionin GBM.545,546 Moreover, it was found that HIF-1αrequires elevated concentrations of heat shock proteins 70 and 90,which induce tumor progression.547