Arachidonate 5-lipo, Xenopus/Amphibian,ygenase (ALO, Xenopus/Amphibian,5) catalyzes the first step in leukotriene biosynthesis and plays a role in inflammatory processes. 5-lipo, Xenopus/Amphibian,ygenase is e, Xenopus/Amphibian,pressed specifically in bone marrow-derived cells. This enzyme catalyzes the conversion of arachidonic acid to 5(S)-hydropero, Xenopus/Amphibian,y-6-trans-8,11,14-cis-eicosatetraenoic acid, and further to the allylic epo, Xenopus/Amphibian,ide 5(s)-trans-7,9-trans-11,14-cis-eicosatetrenoic acid (leukotriene A4). Mutations in the promoter region of this gene lead to a diminished response to antileukotriene drugs used in the treatment of asthma. These mutations are also associated with atherosclerosis and several cancers.