Figure 1.

Detection of (a) MMP-2 and (b) MMP-9 activity in media collected from bovine articular cartilage explants treated with TNF-α or C₂-ceramide for 24 hours. Medium was collected 24 hours after treatment of explants with 100 ng/ml TNF-α or 50 μM C₂-ceramide in the presence or absence of the PKR inhibitor 2-AP (10 mM) and analysed by gelatin substrate zymography. A standard known to contain either MMP-2 or MMP-9 was included (Std). An unidentified enzyme is indicated by '?'. 2-AP, 2-aminopurine; MMP, matrix metalloproteinase; TNF, tumour necrosis factor.