5(S)-HPETE is a monohydroperoxy polyunsaturated fatty acid produced by 5-lipoxygenase metabolism of arachidonic acid and a biosynthetic precursor to leukotrienes. 5(S)-HPETE is described to induce c-fos without inducing c-jun in TA1 cells, suggesting that c-fos induction by TNF may be HPETE-mediated. 5(S)-HPETE is also described to modulate histamine release from human basophils.