To determine the efficacy of Syk inhibitor against SLE, R788 (fostamatinib) was orally administrated for four weeks to 40-wk-old female FcγRIIb−/− mice (symptomatic lupus model) and age-gender matched wide type (WT) mice, to imitate the clinical situation (Fig. 1A). This evidence concerns the gene SYK and systemic lupus erythematosus.