MUC5B and synovial sarcoma: TLR4 recognizes the ectopic occurrence of mucins MUC5B and MUC7 in the SGs of patients with SS, leading to significant increases in CXCL8, TNF‐α, IFN‐α, IFN‐β, IL‐6, and IL‐1b, thereby promoting the chronic state of SS [169].