Motility Related Protein (MRP1) is a member of the superfamily of ATP-binding cassette (ABC) transporters. It can enable ATPase-coupled inorganic anion transmembrane transporter activity. Involved in anion transmembrane transport; renal tubular secretion and response to toxic substance. It is an integral component of plasma membrane. Besides, Heparin Binding Epidermal Growth Factor Like Growth Factor (HBEGF) has been identified as an interactor of MRP1, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human MRP1 and recombinant human HBEGF. Briefly, biotin-linked MRP1 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to HBEGF-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30 min, then wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 μl stop solution to the wells and read at 450 nm immediately. The binding activity of MRP1 and HBEGF was shown in Figure 1, the EC50?for this effect is 6.55 ug/mL.