Figure 1. The network of ROS regulation by p53. Reactive oxygen species (ROS) can modulate the activity of p53, which, in turn, controls the expression of several ROS-regulating genes, such as GPX, PIGs and MnSOD. Those act as either pro- or antioxidant. NCF2, the gene encoding the intercellular subunit of NOX2 protein complex, is also transcriptional activated by p53. Upon activation, NOX2 generates ROS beneficial to cell survival. On the other hand, high ROS concentration may lead to cell death.