FMO5 and neoplasm: In an autochthonous mouse uterine cancer model, infiltrated neutrophils exhibited N2-like phenotypes and released neutrophil elastase (NE) to promote tumor growth, and improved tumor oxygenation converted neutrophil phenotypes to N1-like one with a higher ability to kill tumor cells by producing NADPH oxidase-derived reactive oxygen species (ROS) and matrix metalloproteinase (MMP)-9 [36].