NOX4 and chronic kidney disease: An increase in oxidative stress (Fig. 4A) and a reduction in mRNA levels of the transcription factor Nfe2l2, which stimulates the antioxidant response, was observed beginning in the initial stage of the AKI to CKD transition (Fig. 4B), even though Nox4 mRNA levels were reduced in the late stage of the disease (Fig. 4C).