PDCD1LG2 and central nervous system cancer: Thus, coexpression of CD44 and checkpoint family members were checked in glioma, and we found that CD44 expression positively correlates with the expression level of PD-L1 and PD-1 and correlates with the expression level of PDCD1LG2 (namely PD-L2) as well in the TCGA and CGGA glioma datasets (Supplementary Figure 10).