NADPH oxidase is a major source of the superoxide produced in cardio-vascular tissues. Expression of NOX1, a catalytic subunit of NADPH oxi-dase, is induced by various vasoactive factors, including angiotensin II, prostaglandin (PG) F2a and platelet-derived growth factor (PDGF). To clarify the molecular basis of this transcriptional activation, we delineated the promoter region of the NOX1gene.