PDCD1 and glioblastoma: We then explored the relationship between CD147 expression and classic immune checkpoints, such as SIGLEC15, TIGIT, CD274, HAVCR2, PDCD1, CTLA4, LAG3, and PDCD1LG2 (Figure 5C), which indicated that most of these immune checkpoints had a close correlation with CD147 expression levels, especially in BLCA, GBM, KIRC, PAAD, PRAD, LUSC, SKCM, and THCA.