KRAS and neoplasm: Indeed, oncogenic KRAS can regulate metabolic changes and alter cellular signalling, both of which can increase the production of intracellular reactive oxygen species (ROS), but at the same time, it also upregulates antioxidant systems to balance ROS to levels at which they are beneficial for tumour development and progression, while remaining below the threshold that causes cell death.65 KRAS can upregulate ROS through multiple mechanisms.