To investigate the role of 5-LOX in rheumatoid arthritis, human synovial fibroblasts were pretreated with 5-LOX inhibitors NDGA (5 and 10 μM) and MK-886 (5 μM) for 1 hr and then treated with TNF-α (10 ng/ml) for next 6 hr. Here, ALOX5 is linked to rheumatoid arthritis.