PDCD1 and central nervous system cancer: Both transporters closely interact with immunoinhibitory checkpoints (PD‐1/PD‐L1/PD‐L2, T‐cell immunoglobulin and mucin‐domain containing‐3) and cytokines (TGF‐β, IL‐10), and SLC16A3 levels further correlate with those of neutrophil activation markers and chemokines (e.g., CCL2, CXCL8), thereby promoting the recruitment of suppressive immune cells into the glioma microenvironment [164].