In both glioblastoma multiforme (GBM) and lower-grade glioma (LGG), ALPK1 showed a significant positive association with four immune checkpoints: PD-L1 (CD274), CTLA-4, LAG-3, and PD-1 (PDCD1) (Figures 8B, C). Here, PDCD1 is linked to glioblastoma.