In addition, the function of CTL in the tumor bed can be inactivated by inhibitory mediators, such as IL10, IDO1, reactive oxygen species (ROS), and nitric oxide (NO) released from immune-suppressive Treg and MDSC [185] (Figure 1C), indicating synergistic networking among so-called hijacked immune cells conveys tumor-promoting outcomes. The gene discussed is IDO1; the disease is neoplasm.