CLDN5 and colitis: To exclude the possibility that the increased susceptibility of hMRP8 Vhl KO mice to DSS-induced colitis was caused by barrier defects associated with hMRP8 Vhl KO, we examined barrier proteins, including occludin (OCN) and claudin 5 (CLDN5), in the colon of mice fed with water, and observed that there were no significant differences in the expression of these proteins between hMRP8 Vhl KO and WT mice (Fig. 5D).