Figure. The binding activity of MK with LRP1.<br/>Midkine (MK) also known as neurite growth-promoting factor 2 (NEGF2) is a protein that in humans is encoded by the MDK gene. MK is a basic heparin-binding growth factor of low molecular weight, and forms a family with pleiotrophin. It is pleiotropic, capable of exerting activities such as cell proliferation, cell migration, angiogenesis and fibrinolysis. MK may potentially be indirectly targeted as a cancer treatment as a result of its cancerous proliferation properties. Besides, Low Density Lipoprotein Receptor Related Protein 1 (LRP1) has been identified as an interactor of MK, thus a binding ELISA assay was conducted to detect the interaction of recombinant human MK and recombinant human LRP1. Briefly, MK were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100uL were then transferred to LRP1-coated microtiter wells and incubated for 2h at 37℃. Wells were washed with PBST and incubated for 1h with anti-MK pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50µL stop solution to the wells and read at 450nm immediately. The binding activity of MK and LRP1 was shown in Figure 1, and this effect was in a dose dependent manner.