CD44 and glioblastoma: Further crossing these 34 genes with 840 genes that were positively correlated with PD-L1 expression (p < 0.05; r > 0.3) from the Ivy Glioblastoma Atlas Project, 7 genes were eventually sorted out, namely GBP5, ICAM1, CAMK2D, IRF1, SOCS3, CD44, and CCL2 (Fig. 5a).