TBX21 and Autoimmunity: Given published data showing an indispensable role of IFN-γ–STAT1–Tbet signaling in the development of autoimmune AFC and GC responses and autoimmunity in SLE-prone mice (4, 24, 25, 42) and regulation of STAT1 in B cells by the STAT4 risk allele of rs11889341 (48), it is tempting to speculate whether STAT1, and not STAT4, is the culprit gene in promoting SLE autoimmunity in patients.