CASP9 and neoplasm: The genes analyzed, BCL2, BCL2L1, BAK1, BAX, PTEN, TP53, MDM2, CASP9 and VEGFA, play key roles in fundamental processes for the survival and proliferation of GB tumor cells and are involved in three different pathways: the intrinsic apoptotic pathway (mitochondrial pathway), the TP53 pathway and the PI3K/AKT/mTOR pathway, all contributing to tumor growth, drug resistance and the ability of the tumor to evade programmed cell death [37,38,39,40,41].