MMP9 and central nervous system cancer: The WB results also showed that GBE1 knockdown caused the downregulation of the invasion-related protein MMP9, the angiogenesis-related protein HIF1α, VEGFa, and the apoptosis inhibitor protein Bcl-2, and increased the expression of Bax and Cleaved-Caspase-3, further confirming the node role of GBE1 in the regulation of the biological behavior of glioma (Figure 4C,D).