Its ligand, Galectin-9 (Gal-9) is expressed on cancer cells, and the complex formed by the checkpoint TIM-3 and its ligand Gal-9 induces apoptosis of Th1 cells [25, 26], and, consequently, a reduction in CD8+ T cells whose proliferation depends on Th1-secreted IL-2. This evidence concerns the gene LGALS9 and cancer.