STAT2 and systemic lupus erythematosus: Moreover, the expression levels of IRF1, STAT1, and STAT2 were significantly increased in the SLE samples (IRF1, HC vs. SLE, P < 0.05; STAT1, HC vs. SLE, P < 0.001; STAT2, HC vs. SLE, P < 0.05), although an increase in STAT2 expression alone was detected in the DM samples (HC vs. DM, P < 0.01) (Fig. 2B).