Cytotoxicity of DHMEQ. Significant cytotoxicity was not observed in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) treated with dehydroxymethylepoxyquinomicin (DHMEQ). Cells were stimulated with 5 ng/ml tumor necrosis factor (TNF)-α and incubated in serum-free medium for 14 hours with 0–10 μg/ml DHMEQ or with the apoptosis inducer staurosporin (1 μmol/l), and Cy3-labeled annexin V binding cells were measured by flow cytometry. Data shown are representative of three independent experiments. MFI, mean fluorescence intensity.