 The double oxygenations may be conducted within a single cell type which possess ALOX5 and an enzyme with 15-lipoxygenase activity or, alternatively, by two different cell types, each of which possesses one of these enzyme activities.In the latter transcellular biosynthetic pathway, one cell type forms either the 5,6-dihydroxy-, 5-hydroxy, 14,15-dihydroxy- or a 15-hydroxy-eicosatetraenoate, and then passes this intermediate to a second cell type, which metabolizes it to the final LX product.For example, LXs are formed by platelets which, lacking ALOX5, cannot synthesize them.