Jahnel et al. (2014) reported decreased ABCG2 mRNA levels in Crohn’s disease compared to healthy controls, whereas both ABCC3 and ABCC4 mRNA was decreased in ulcerative colitis in their study. However, the in vivo effect of these transporter changes on conjugate kinetics remains to be elucidated. This evidence concerns the gene ABCG2 and ulcerative colitis.