LGALS9 and neoplasm: Gal-9, a ligand of TIM-3 as a type of T cell surface inhibitory molecule specifically expressed on Th1 cells, mainly binds to TIM-3 positive cells to play suppressive roles in anti-tumor immunity, such as inhibiting the amplification of Th1 and Th17, promoting the apoptosis of Th1 cells and inducing the exhaustion of CD8+ T cells.