To confirm the antigenic structure that was targeted by autoAb present in RA sera, we analyzed their reactivity against the citrullinated peptides identified by MALDI-TOF MS analysis on the different deiminated proteins (aldolase, α-enolase, PGK1, HSP60, FUSE-BP1 and FUSE-BP2), although it was expected that not all identified sequences described in Table 3 were, or carried, B-cell epitopes. This evidence concerns the gene PGK1 and rheumatoid arthritis.