The investigators have identified several possible beneficial mechanisms of effect of low-dose NO donors for cancer management. We have recently published the positive effect of effect of NO signalling (with GTN as the effector molecule) on cancer immune surveillance. The major histocompatibility complex class I chain-related (MIC) molecules, MICA and MICB, play important roles in tumor surveillance by NK cells, lymphokine-activated killer (LAK) cells, and cytotoxic T cells. While MICA is absent from most normal tissues, they can be induced by cellular stresses, such as exposure to carcinogens and infection, and are expressed in a broad range of carcinomas and some haematopoietic malignancies. In humans, the interaction of cell surface MIC molecules with the C-type lectin-like NKG2D receptor on NK, LAK and effector T cells leads to the activation of innate and adaptive immune responses with the subsequent lysis of the tumor cells. Thus, it has been proposed that MIC-NKG2D interactions are critical to the immune surveillance function of NK, LAK and cytotoxic T cells.