APEX1 and systemic lupus erythematosus: Although no significant difference was identified on the levels of the 16 selected autoAbs between SLE-LN+ and SLE-LN−, two of the IgG autoAbs (anti-HMGB1 and anti-APEX1) showed a clear trend of increased expression in SLE-LN+ compared with SLE-LN− as shown in Figure 5G and H. As a control, the anti-dsDNA antibody level was significantly higher in lupus nephritis patients compared to SLE patients without nephritis (P = 0.018, Figure 5I).