LGALS9 and melanoma: The single cell data showed Gal-9 (LGALS9) was higher expressed on the melanoma cells and immune cells (such as cytotoxic T cells, exhausted T cells, Treg, T memory cells, B cells, NK cells and monocytes) (Fig. 1c), and its receptor TIM-3 (HAVCR2) was relatively much higher expressed on the cytotoxic T cells, NK cells and exhausted T cells (Fig. 1c), moreover the cell communication in TME (Fig. 1b) exhibited that Gal-9/TIM-3 may be the key reason for cytotoxic T cells exhausting as well, thus leading to immune escape of acral melanoma.