TP53 and neoplasm: NO mediates tumour promotion through genotoxic reactions (DNA damage), anti-apoptotic activity (regulation of caspases and death-associated proteins), regulation of the NO/NOS2–p53 axis, which is critical in defining the apoptotic mechanisms of tumours, upregulation of angiogenesis (production of proangiogenic factors), metastatic actions (overexpression of MMPs and VEGF), and suppression of the immune response (reduction in leukocyte infiltration) [30,35].