We thank Drs. Glenn Dranoff, Jeffrey A. Whitsett and Bruce C. Trapnell for providing GM-CSF−/− mice; Dr. Hiroyuki Kagechika for supplying Am80; Dr. Isao Okayasu for the induction protocols and analysis of DSS colitis; Dr. Toshiaki Ohteki for valuable comments; and Noriko Uemura, Naoko Maeda, Tomoko Warita, and Miwako Oda for technical and secretarial assistance. This evidence concerns the gene CSF2 and colitis.