Intriguingly, we detected increased levels of Cox-2 and β-catenin, a downstream PGE2 target, in CRC tissues and sorted IECs from IEC-miR-146a−/− mice (Fig. 4k, l) and miR-146a−/− mice (Supplementary Fig. 4j, k). Here, PTGS2 is linked to colorectal carcinoma.