HAVCR2 and melanoma: The results in Fig. 1c exhibited that LGALS9 was higher expressed on the tumor cells (melanoma cells) and immune cells (such as T cells (cytotoxic T cells, exhausted T cells, Treg, T memory cells), B cells, NK cells and monocytes), but its receptor HAVCR2 was relatively much higher expressed on the cytotoxic T cells and NK cells which have been evidenced as the main tumor killers in vivo11,33.