Celecoxib-induced cell death in rheumatoid arthritis fibroblast-like synoviocytes is caspase-independent. Effect of caspase inhibition on celecoxib-induced cell death using a higher concentration of caspase inhibitor (a) and a lower concentration of celecoxib (40 μM) (b). In these conditions, inhibition of cell death could not be observed. Representative data of three different experiments are shown. NS, unstimulated cells; TRAIL, tumor necrosis factor-related apoptosis-inducing ligand.