花生四烯酸
The Arachidonic acid + O2 → 15"(S)"-HpETE → EXA4 → EXC4 → EXD4 → EXE4) metabolic pathway is analogous to the leukotriene-forming pathway (i.e. Arachidonic acid + O2 → 5(S)-HpETE → LTA4 → LTC4 → LTD4 → LTE4). EXA4, similar to LXA4, is viewed as an intracellular intermediate that is rapidly converted to down-stream products while EXC4, EXD4, and EXE4, similar to LTC4, LTD4, and LTE4, are regarded as extracellular agents which stimulate cell function.