ARPP21 and glioblastoma: With the strict threshold, 6 highly expressed genes were screened in GBM, including AFF2, GNAL, ARPP21, CACNA2D3 and RGS7, in addition to 6 highly expressed genes in OD, including CNTN2, ABCA6, MEGF11, DOCK5, MOXD1 and TRIM67. Finally, by constructing a PPI network of DEGs, it was demonstrated that TP53 and HIST1H3A were the hub nodes in the PPI network of GBM and CNTN2 was the hub node in OD.