STAT1 and systemic lupus erythematosus: By crossing autoimmune-prone B6.Sle1b and SLE disease-prone B6.Sle1b.Yaa mice to the B6.STAT1-S727A mutant strain [77], in which serine 727 in STAT1 is replaced with alanine, we recently discovered the role of STAT1-pS727 in promoting systemic autoimmunity and SLE disease by regulating AFC, GC, Tfh, and autoantibody responses [78].