CXCR4 regulates circadian rhythmic oscillations of monocytes. (A) Representative FACS plot of CXCR4 and CD11b expression by blood Ly6C^hi monocytes (gating strategy in Fig. S4) of one out of four independent experiments. (B) Representative FACS plot depicting loss of CXCR4 expression in Lyz2^creCxcr4^fl mice (blue) as compared with Cxcr4^fl controls (red) of one out of three independent experiments. (C) Comparison of blood leukocyte populations in Rosa^mT/mG:Lyz2^cre mice and Rosa^mT/mG:Lyz2^creCxcr4^fl mice showing the percentage of Lyz2-cre mediated recombination (GFP⁺) at the Rosa26 locus (left) and normalized CXCR4 MFI (arbitrary units) of circulating leukocyte subsets (right). Results are expressed as mean ± SD (n = 4–5 mice per group). ns, not significant; *, P < 0.05; **, P < 0.01; ****, P < 0.0001 (two-way ANOVA). (D and E) Blood Ly6C^hi (D) and Ly6C^lo (E) monocyte values of normalized CXCR4 MFI on Cxcr4^fl control mice (left) and counts between Cxcr4^fl control and Lyz2^creCxcr4^fl mice (right) were quantified at ZT5 and ZT13. Data are representative of one out of three experiments. Results are expressed as mean ± SD (n = 5 mice per group). ns, not significant; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 (Student’s t test).