Past and present studies implicate the cytochrome P450 (CYP) Arachidonic Acid (AA) Epoxygenase Pathway in hormonal signaling, cell proliferation, angiogenesis, the regulation of vascular tone and tubular ion transport;and suggested roles for the enzymes and the epoxy-acid (EETs) in the pathophysiology of diseases such as hypertension and cancer.To explore the physiological/pathophysiological relevance of these studies, a line of Cyp2c44 epoxygenase gene knockout mice (Cyp2c44 KO) were developed as in vivo models of monogenic dysfunction.