ABCG2 and chronic kidney disease: For evaluation of protein expression in human biopsies, immunohistochemistry of HIF1α, which showed a negative correlation with eGFR on transcriptomic level, and ATP binding cassette subfamily G member 2 (ABCG2) as well as VEGFA, both positively correlating with eGFR, was performed on a set of kidney biopsies of patients with CKD with normal and reduced eGFR (Fig. 1, Supplementary Figure 2).