HPBzyme inhibits ECM degradation and apoptosis of chondrocytes. (a) MMP3 mRNA level as determined by qRT-PCR. (b) MMP13 mRNA level as determined by qRT-PCR. (c) COL2 mRNA level as determined by qRT-PCR. (d) Aggrecan mRNA level as determined by qRT-PCR. (e-i) Effects of HPBzyme on the MMP-3 and -9, Caspase-3 and -9 protein levels after IL-1β induction as determined by Western blotting analyses. Protein levels were normalized to that of GAPDH. (j) Immunofluorescence staining of the effects of HPBzyme on the MMP-9 level after IL-1β stimulation. magnification, × 200, Bar, 100 μm. (k) Effect of HPBzyme on proteoglycans in chondrocytes after IL-1β stimulation as determined by safranin O staining, Bar, 1 cm. Data are means ± SD, n = 3. *P < 0.05 vs. blank group (chondrocytes without HPBzyme and IL-1β), #P < 0.05 vs. IL-1β group (chondrocytes with only IL-1β stimulation).