A cytochrome P450 monooxygenase involved in the metabolism of arachidonic acid and its oxygenated derivatives (PubMed:14634044, PubMed:9344476, PubMed:17418803). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase) (PubMed:14634044, PubMed:9344476, PubMed:17418803). Participates in the conversion of arachidonic acid to omega-hydroxyeicosatetraenoic acid (20-HETE), a signaling molecule acting both as vasoconstrictive and natriuretic with overall effect on arterial blood pressure (PubMed:14634044). Hydroxylates the terminal carbon (omega-hydroxylation) of inflammatory lipid mediators, including prostaglandin (PG) A1, PGE1 and leukotriene B4 (LTB4), and may play a role in inactivation of these oxylipins during the resolution of inflammation (PubMed:14634044, PubMed:9344476, PubMed:17418803). (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 + reduced [NADPH--hemoprotein reductase] = 20-hydroxy-(5Z,8Z,11Z,14Z)-eicosatetraenoate + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] leukotriene B4 + O2 + reduced [NADPH--hemoprotein reductase] = 20-hydroxy-leukotriene B4 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 6-trans-leukotriene B4 + O2 + reduced [NADPH--hemoprotein reductase] = 20-hydroxy-6-trans-leukotriene B4 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + prostaglandin A1 + reduced [NADPH--hemoprotein reductase] = 20-hydroxy prostaglandin A1 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + prostaglandin E1 + reduced [NADPH--hemoprotein reductase] = 20-hydroxy prostaglandin E1 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Expressed in hepatocytes (PubMed:17418803). High expression in liver and kidney. Lower expression in brain (PubMed:9344476). Up-regulated in hepatocytes by pro-inflammatory cytokine IL6 and down-regulated by anti-inflammatory cytokine IL10. Belongs to the cytochrome P450 family.