The intersection of all protein lists containing the respective higher reactive DIRAGs revealed 8 proteins (EEF1A1, HBP1, TXNDC5, TPM3, c8orf33, ILF3, MGEA5, LTBP3, HLA-C and UBA1) higher reactive in seropositive RA, seronegative RA and PIA (Figure 3A, not corrected for duplicated proteins). Here, UBA1 is linked to rheumatoid arthritis.