Cellular oxidative and electrophilic stress caused by drugs and other xenobiotics, inflammation, and ionizing radiation are associated with an accumulation of reactive oxygen species and electrophilic insults, which contribute to the pathogenesis of various diseases such as cancer, neurodegenerative disease, and atherosclerosis. In order to protect cells from reactive oxygen species and electrophilic insults, the endogenous cellular antioxidant defense system initiates a response to cellular oxidative and electrophilic stress. NRF2 (nuclear factor (erythroid-derived 2)-like 2; NFE2L2) is a key transcriptional factor regulating hundreds of antioxidant and Phase II detoxification genes. Under normal conditions, NRF2 is sequestered in the cytoplasm through binding with Keap1, an actin-binding protein and finally is degraded through the Keap1-dependent ubiquitination. In response to a stimulus, degradation of Keap1 is markedly increased. This leads to the disruption of the Keap1-NRF2 complex and nuclear translocation of NRF2. NRF2 then dimerizes with small Maf proteins and binds to the ARE (antioxidative response element) in promoters of downstream genes to initiate expression. Accurate monitoring of the level of activated NRF2 in cells, tissues or animal models is required for investigating signal transduction pathways and other research applications such as drug development. Simple, speedy and high-throughput methods are required for this purpose. The NRF2 Transcription Factor-Activity Assay kit is a non-radioactive transcription factor assay with an ELISA format. It offers an easy, speedy, sensitive and high-throughput method to detect the activation of transcription factors.