Fig. 1From: Blockade of novel immune checkpoints and new therapeutic combinations to boost antitumor immunityCoinhibitory receptors expressed by cytotoxic T lymphocytes (A) and natural killer cells (B) and their ligands. Cytotoxic T lymphocytes and natural killer cells can express multiple coinhibitory receptors, known as immune checkpoints, that produce downstream inhibitory signals when activated upon binding to their ligands. Note that not all ICs are expressed simultaneously by cytotoxic T lymphocytes or NK cellsBack to article page