HPGD and malignant colon neoplasm: Interestingly, the expression of COX-2 was significantly increased in the AOM+DSS group (p < 0.05, Figure 6F), whereas that of 15-PGDH, a prostaglandin-degrading enzyme that is highly expressed in normal colon mucosa but is ubiquitously lost in human colon cancers [20], was significantly decreased in the AOM+DSS group (p < 0.05, Figure 6F).