Suppressive effects of PIP-18 versus sPLA2 and MMP inhibitors on MMP secretion. Osteoarthritis (OA) and rheumatoid arthritis (RA) synovial fibroblast (SF) cells were incubated for one hour with 5 μM phospholipase inhibitor from python (PIP)-18, matrix metalloproteinase (MMP)-II inhibitor or secretory phospholipase A2(sPLA2) inhibitor LY-315920, stimulated overnight with rhIL-1β (10 ng/ml), and supernatants assayed for MMP secretions by ELISA: (a) MMP-1, (b) MMP-3, (c) MMP-2, (d) MMP-9, (e) tissue inhibitor of metalloproteinase (TIMP)-1, (f) TIMP-2. Results are the mean ± standard error of the mean of the combined data of triplicate determination of triplicate experiments done on a pool of RA SF cultures from five RA patients. Bonferroni's post hoc test was done only if the analysis of variance single-factor test was found significant. *P < 0.05, **P < 0.01, ***P < 0.001 for pair-wise comparisons (IL without inhibitor versus IL with each of the inhibitor used in the study.