Liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin), expressed in the liver and on multiple tumor types (e.g., melanoma), suppresses anti-tumor immunity by binding LAG-3 on CD8+ T cells, where its KIEELE motif has been identified as structurally and functionally essential for LAG-3’s inhibitory capacity. This evidence concerns the gene LAG3 and neoplasm.