PTGR1 and colorectal carcinoma: 12-keto-LBT4, an inactive product of LBT4 conversion via LTB4–12-hydroxydehydrogease/15-oxo-prostaglandin-13-reductase (LTB4DH/15oPGR), was shown to be considerably downregulated in CRC patients sera, and thus, has been proposed as a potential biomarker of this malignancy [153].