Biglycan, also known as BGN, is a a small leucine-rich repeat proteoglycan (SLRP). It can be detected in a variety of extracellular matrix tissues, including bone, cartilage and tendon. Biglycan consists of a protein core containing leucine-rich repeat regions and two glycosaminoglycan (GAG) chains consisting of either chondroitin sulfate (CS) or dermatan sulfate (DS). Non-glycanated forms of biglycan (no GAG chains) increase with age in human articular cartilage. Biglycan interacts with collagen, both via the core protein and GAG chains. Biglycan plays a role in the mineralisation of bone. Biglycan core protein binds to the growth factors BMP-4 and influences its bioactivity. To test the effect of BGN on cell apoptosis, 3T3-L1 cells were seeded into triplicate wells of 96-well plates and allowed to attach overnight, then the medium was replaced with various concentrations of recombinant human BGN. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 µl of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 1h at 37℃. Proliferation of 3T3-L1 cells after incubation with BGN for 72h observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with recombinant human BGN for 72h. The result was shown in Figure 2. It was obvious that BGN significantly inhibit cell viability of 3T3-L1 cells. The ED50 is 0.89 μg/mL.