Exposure of human kidney-2 cells (HK-2, a proximal tubule cell model) to sera obtained from rats with CKD resulted in significant downregulation of the protein expression levels of OAT3, OATP1 and P-gp, whereas levels of MRP2, MRP4 and OATP2 were significantly upregulated [22]. The gene discussed is PGP; the disease is chronic kidney disease.