CD8A and neoplasm: After chemokine-mediated infiltration of MDSCs in TME, infiltrated MDSCs increase the activity of signal transducer and activator of transcription 1 (STAT1), reducing the levels of reactive oxygen species (ROS) and increasing the levels of inducible nitric oxide synthase (iNOS), nitric oxide (NO), and arginase-1, inhibiting CD8+ T cells in the tumor [55,64].