Recombinant proteins and representative results of Western blotting. Recombinant LRP2 F2–F7 fragments, CD69, and maltose-binding protein (MBP) were separated by 12.5% SDS–PAGE and were transferred onto nitrocellulose membranes. The membranes were stained with Ponceau S (top panel) or reacted with serum samples diluted at 1:100 (lower five panels). Representative results from patients with RA (RA-18, RA-19 and RA-21), SLE (K-23), and SSc (SSc-85) are shown. RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SSc, systemic sclerosis.