Gelatin zymography gel comparing MMP-2 and MMP-9 production in the supernatant of untreated fibroblast-like synoviocytes isolated from a patient with rheumatoid arthritis (RA-FLS; control) and paxilline-treated RA-FLS incubated in the presence of 0, 1, 5, or 10% of fetal bovine serum. Paxilline-treated RA-FLS exhibit a decrease in MMP-2 production when incubated without serum. This effect is masked by incubation with 1, 5, 10% serum.