SNRPD1 and systemic lupus erythematosus: 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.