Fig. 6

Cell viabilities after RNA interfering of Per2 and Bik, and long-term expression of Per2 and Bik mRNA under MTX treatment. a After transfection with Per2 or Bik siRNA, cells treated with MTX (10, 100 nM) or control media for 24 h to measure cell viabilities. Cell viabilities of control (MTX-untreated cells) defined as 1.0, and each value shown relative to control. Values are mean ± SEM. *p < 0.05, **p < 0.01, n = 5. b Long-term expression of Per2 and Bik. After 8, 16, 24, and 32 h of culture in serum-free media, mRNA was extracted from synovial fibroblasts to measure expressions of Per2 and Bik. Values are mean ± SEM. *p < 0.05, #p < 0.1, n = 5. c Reduction rate of cell viabilities under time-dependent MTX treatments. Viabilities of synovial fibroblasts after treatment with 10 nM of MTX at 0–8 h (lower Per2/Bik expression period) or 24–32 h (higher Per2/Bik expression period) measured, respectively. Cell viabilities of MTX-untreated cells defined as 100%, and values are mean ± SEM. *p < 0.05, n = 5. Bik Bcl-2 interacting killer, mRNA messenger RNA, MTX methotrexate, Per period