BCR and synovial sarcoma: It has been argued that RF-expressing MALT lymphomas experience chronic NF-κB pathway signaling as a result of dual RF-BCR/TLR stimulation, for example, in SS sialadenitis by IgG-SSA/SSB complexes containing single-stranded RNA stem-loop structures as TLR7 ligands (Bende et al, 2009, 2020, 2023).