PDCD1LG2 and cancer: To explore whether PD-L2 plays an important role in immunosuppression of cancer, we examined the expression levels of both PDCD1LG1 and PDCD1LG2 from The Cancer Genome Atlas (TCGA), and found that PDCD1LG2 exhibited higher expression levels than PDCD1LG1 in multiple types of cancers including ccRCC (Fig. S1A), a major type of RCC [13, 14].