Autoantibodies to BRAF recognize four linear peptides P10, P16, P25, P33. Anti-BRAF autoantibodies from the sera of 20 RA patients were tested for binding to BRAF peptides by ELISA. After washing, peroxydase conjugated anti-human IgG was added. Optical density was read at 405 nm. Background OD was obtained by adding each serum to a well without peptide. Positive sera were defined by OD value higher than twice background OD (in blue).