Fifteen human proteins were selected, because they appeared in ≥30% of NPSLE patients with >90% specificity relative to the controls (Table 1).Given that anti-Sm, anti-rRNP, and anti-PCNA autoantibodies were frequently detected in the serum of SLE patients, the autoantigens recognized by these autoantibodies, including SNRPB (small nuclear ribonucleoprotein polypeptides B and B1), SNRPD1 (small nuclear ribonucleoprotein D1 polypeptide), RPLP0, RPLP1, RPLP2, and PCNA, were also included in the focused autoantigen microarray. This evidence concerns the gene PCNA and systemic lupus erythematosus.