PGE₂ is responsible for decreased MMP-1 activity.

<p>(A) Active MMP-1 content in human small and large diameter varicosities (paired SDv and LDv, n = 6) and healthy saphenous veins (SV, n = 4) after 24 h of incubation. Treatments with either PGE₂ 10 µmol/L or GW62768X 1 µmol/L are represented by hatched bars. (B) Total MMP-2 content in varicose veins (n = 5) and SV (n = 4) after 30 min of incubation. Values were determined by EIA in supernatants and normalized by tissue wet weight; * P<0.05 as determined by one-way-ANOVA followed by the Tukey post-hoc test and by a paired t-test for varicose veins.