PTGS2 and cancer: Whereas 15-(S)-HETE has been shown to be involved in the process of inflammation, angiogenesis, and the pathogenesis of cancer, especially CRC [153–159], 15-(R)-HETE can be converted to, i.e. 15 epi-lipoxin A4 or B4 by leukocyte 5-lipoxygenase in a transcellular process during the interaction of COX-2-expressing endothelial or epithelial cells with polymorphonuclear leukocytes [151].