LGALS9 and neoplasm: Gal-9 was identified as the first TIM-3 ligand that is highly expressed in immune system tissues, such as lymph nodes, bone marrow, thymus, and spleen, and can also be secreted by tumor cells, endothelial cells, and other cells and interacts with oligosaccharides on the TIM-3 IgV domain (7, 14, 16).