Receptor Tyrosine Protein Kinase erbB-2 (ErbB2) as known as HER2 (Human Epidermal Growth Factor Receptor 2), is a member of the EGFR family of receptor tyrosine kinases. It is a 185 kDa cell membrane receptor that plays a crucial role in cell signaling and proliferation.Besides,Plakophilin 2 (PKP2) has been identified as an interactor of ErbB2, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human ErbB2 and recombinant human PKP2. Briefly, ErbB2 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to PKP2-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-ErbB2 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, 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 450/630nm immediately. The binding activity of recombinant human ErbB2 and recombinant human PKP2 was shown in Figure 1, and this effect was in a dose dependent manner.