EGF and EGFR are expressed in RA and CIA. A, EGF concentration was measured in serum from normal controls (n = 20) and RA patients (n = 30) by ELISA (**P <0.01). RA synovial tissue was sectioned and examined for EGFR staining (B) in the synovial lining and (C) in the subsynovial tissue. RA synovial tissue was examined for (D) phosphorylated (p)-EGFR (Y1068) expression. E, Paws from mice with CIA (score 4) were stained for EGFR and (F) p-EGFR (Y1068). Pictures represent areas of pannus surrounding the bone next to inflammatory foci. B-F, Control sections indicate adjacent sections stained with appropriate isotype control antibodies. A-C, Data represent two experiments. E and F, Data represent at least four experiments. Bars represent 50 μm.