CXCL12 and systemic lupus erythematosus: CXCR4 expression was increased on basophils from aged Lyn−/− animals as were CXCL12 and 11β-PGF2α serum titers when compared to their WT counterparts (Fig. 4b–d and Supplementary Fig. 4a–c), mimicking differences between patients with SLE and HC (Figs. 1−, 3).