<h4>Objectives</h4>This study investigated the role of TGF-β-activated kinase 1 (TAK1) in synovial inflammation and hyperplasia in JIA synovial fibroblasts (JIASFs).<h4>Methods</h4>Patient-derived JIASFs were treated with TNF-α, IL-1β and IFN-γ with and without various TAK1 inhibitors. Here, IL1B is linked to juvenile idiopathic arthritis.