C1GALT1 and colitis: The importance of core 3 is highlighted in the generation of compound mutant IEC C1galt1−/−; C3GnT−/− (DKO) which show a rapid disintegration of the encapsulating mucus and accelerated onset of colitis after weaning, associated with a complete truncation of all O-glycans throughout the colon.53 These mice revealed the important principle that the degree of O-glycosylation impacts mucus functions and colitis potential.