PTGS2 and diabetic kidney disease: A previous study reported that AhR acts as a nuclear transcriptional factor that binds to the promoters of cyclooxygenase 2, FN, collagen IV and connective tissue growth factor, stimulates the expression of these genes, and thus initiates mesangial cell proliferation, renal glomerular fibrosis and macrophage infiltration in mice with diabetic nephropathy.[38] To our surprise, AhR was hardly detected in the nucleus either by Western blot or immunofluorescence in our study.