Procollagen II N-Terminal Propeptide is specific for cartilaginous tissues. It is essential for the normal embryonic development of the skeleton, for linear growth and for the ability of cartilage to resist compressive forces, which was are associated with achondrogenesis, chondrodysplasia, early onset familial osteoarthritis, Langer-Saldino achondrogenesis, SED congenita, Kniest dysplasia, Stickler syndrome type I, and spondyloepimetaphyseal dysplasia Strudwick type. A binding ELISA assay was conducted to detect the association of PIINP with ITGb1. Briefly, ITGb1 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul ITGb1 were then transferred to PIINP-coated microtiter wells (2ug/ml, 100ul/well) and incubated for 1h at 37 ℃. Wells were washed with PBST and incubated for 1h with anti-ITGb1 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 uL stop solution to the wells and read at 450nm immediately. The binding activity of PIINP with ITGb1 was shown in Figure 1, and this effect was in a dose dependent manner, the EC50 was approximately 2.82 ug/mL.