PDCD1LG2 and cancer: Similarly, PD-L2 (PDCD1LG2: programmed cell death 1 ligand 2) is an immune checkpoint that contributes to immunosuppressive microenvironment for cancer [166]; its expression is reversely correlated with RKIP expression in PC (Spearman r = −0.384, p < 2.2 × 10−16) (Figure 5).