NFE2L2 and lung cancer: Since NRF2 transcriptionally regulates the activity of system xc-, as well as expression of SLC7A11 and glutathione metabolism [199], 18F-FSPG PET provided a sensitive and specific marker of NRF2 activation (NRF2D29H) in orthotopic, patient-derived, and genetically engineered mouse models of lung cancer [200].