HSPA5 and rheumatoid arthritis: The RA patient serum antibody levels to GRP78279–298 R289citrulline (P12), GRP78295–314 R305 citrulline (P15) and GRP78500–519 R510citrulline (P23) were significantly increased compared with those of native peptides in RA patients, demonstrating their significance for antibody recognition in RA, in particular the epitope contained in peptide P23 in the GRP78 C-terminal region [41].