Proteolytic activity is decreased in absence of CD40. (A) Gelatinase/collagenase activity in ligated carotid arteries of CD40^−/− mice versus controls. Per group, 2 pools of 6 carotid arteries were used and assayed in duplo (total of 4 measurements per group). Fluorescence was measured at 515 nm after 24, 48, and 72 hours of digestion, and average protease activity was calculated for both groups. (B) Real-time PCR of MMP-2, 9, 13, 14 and TIMP-2 and -3 on ligated carotid arteries of CD40^−/− and wild-type mice reveals a decrease in MMP-2 and -9 levels and an increase in TIMP-2 and -3 levels. (C) Zymography for MMP-2 and -9 reveals a decrease in MMP-2 and -9 activity in CD40^−/− mice compared with wild-type mice, and in CD40-T6 mice compared with CD40-Twt mice. Error bars represent SEM.