ABCG2 and chronic kidney disease: Although the CKD condition increased plasma concentrations of the two compounds in both wild-type and Abcg2-knockout mice, Abcg2-knockout mice showed stronger responses compared with wild-type mice for both indoxyl sulfate and hippuric acid (4.9-fold and 4.4-fold for indoxyl sulfate and hippuric acid, respectively, on day 27) (Fig. 2b,c).