Insulin Like Growth Factor Binding Protein 2 (IGFBP2) is a key member of the IGFBP family that modulates the bioavailability and activity of insulin-like growth factors (IGF-I and IGF-II). Primarily secreted by the liver, IGFBP2 binds IGFs with high affinity, prolonging their half-life while regulating their interaction with IGF receptors. Beyond its classical IGF-regulatory role, IGFBP2 exhibits IGF-independent functions in cell migration, apoptosis, and angiogenesis through interactions with integrins and extracellular matrix components. To detect the activity of recombinant IGFBP2, a functional ELISA assay was performed to evaluate the interaction between recombinant mouse IGFBP2 and recombinant human Insulin Like Growth Factor 1 (IGF1).Briefly, IGFBP2 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to IGF1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-IGFBP2 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 mouse IGFBP2 and recombinant human IGF1 was shown in Figure 1, the EC50 for this effect is 0.017 µg/mL.