A cytochrome P450 monooxygenase that metabolizes (5Z,8Z,11Z,14Z)-eicosatetraenoic acid (arachidonate) to primarily produce 12-hydroxyeicosatetraenoic acid (12-HETE). 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--hemoprotein reductase). an organic molecule + O2 + reduced [NADPH--hemoprotein reductase] = an alcohol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 + reduced [NADPH--hemoprotein reductase] = 12-hydroxy-(5Z,8Z,10E,14Z)-eicosatetraenoate + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Lipid metabolism; arachidonate metabolism. Liver. Belongs to the cytochrome P450 family.