PMAIP1 and cancer: Also, the pretreatment of cancer cells with the ROS scavenger NAC reduced several effects seen with the combination of low glucose and metformin, including a significant decrease in the loss of mitochondrion membrane potential, a decrease in the mitochondrial localization of Noxa and a significant inhibition of caspase 3 activity in cancer cells, suggesting that ROS accumulation is associated with Noxa-mediated mitochondrial damage.