GDF15 and colorectal carcinoma: Using COX-2-deficient and NAG-1 transgenic Adenomatous polyposis coli (Apc)Min/+ mice, Iguchi and co-workers reported an inverse relationship between NAG-1 and COX-2/PGE2 in CRC and suggested that the induction of NAG-1 by celecoxib (1,500 ppm for four weeks) might contribute to the chemopreventive action of the compound [27].