SIGLEC15 and central nervous system cancer: Glioma (LGG+GBM) samples downloaded from the TCGA database were divided into PIMEG-low and PIMREG-high groups according to PIMREG expression (high and low expression levels are classified by the median), and we revealed that immune checkpoint genes (including CD274, HAVCR2, PDCD1LG2, SIGLEC15, LAG3 CTLA4, and PDCD1) were overexpressed compared with the PIMREG-low expression group (P < 0.001) (Figure 7I), while TIGIT expression was lower in PIMREG high-expressing glioma patients than in PIMREG low-expressing glioma patients (P = 4.92e-04) (Figure 7I).