Both the parent long chain PUFAs and their EFA metabolites are linked at the sn-2 position to membrane phosphoglyceride subclasses [9, 11]. Therefore they are selectively liberated from plasma membranes by phospholipase A2 activity [5, 12]. Released free fatty acids and EFAs are rapidly reincorporated into cellular membranes contributing to their short half-life in vivo [5, 11, 13]. AA is quite efficiently reincorporated by up to 95% in the cell phospholipids with only a small amount (<5%) left unesterfied [12]. The minor percentage that is not incorporated is free to undergo further metabolism by the cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 enzymes [14] into highly potent bioactive lipid mediators including prostaglandins, leukotrienes, and epoxyeicosatrienoic acids (Figure 1). Compared to the products of the COX and LOX branches of the AA cascade the cytochrome P450 generated epoxyeicosatrienoic acids (EETs) were the last to be discovered in the early 1980s. Thus less is known about these molecules. While the cytochrome P450 family of enzymes is often associated with xenobiotic metabolism, their endogenous roles include steroid metabolism and EETs formation. More recently,
