Pten (phosphatase and tensin homolog) regulates microbe-induced immune responses in the gut. Thus, the intestinal deletion of Pten accelerates colitis development in Il10-/- mice. Since some of ambient pollutants inhibit Pten function, and exposure to ambient pollutants may increase IBD incidence, it is of importance to study how Pten inhibition could affect colitis development in genetically susceptible hosts.