ETS1 is involved in interleukin-1β(IL-1β)-induced Synoviolin (SYN) expression. (a) ETS1 or ETS1-DN expression plasmids were transfected into mouse synovial fibroblasts. Cells were then cultured in medium containing 10 ng/ml of IL-1β for 48 hours. The expression of SYN was detected by Western blotting (top panel). The expression of ETS1 and its mutant was detected with anti-ETS1 antibody (middle panel). The same membrane was stripped and reblotted with anti-actin antibody (bottom panel).(b) The expression level of SYN was quantified. Error bars represent three independent experiments (mean ± standard deviation). ETS1-DN, dominant negative mutant of ETS1.