Consistent with the inflammatory phenotype, Ptpn2−/− (BALB/c-129SJ) mice are more susceptible to endotoxic shock and macrophages are hypersensitive to lipopolysaccharide [26] and IFNγ [19], whereas Ptpn2+/− (BALB/c-129SJ) mice are hypersensitive to dextran sulphate sodium (DSS) and the development of colitis [27]. Here, PTPN2 is linked to colitis.