Fig. 2: CXCR4 is critical for macrophage-mediated stem cell promoting activity.

a F4/80⁺ Mϕ among CD11b⁺ cells (Supplementary Fig. 16c) in control and CXCR4^Mϕ-cKO mammary glands (n = 6, 7, biologically independent samples). b F4/80 and K8 IF staining of control and CXCR4^Mϕ-cKO mammary glands. Enlarged views of boxed areas are shown. c Quantification of intraepithelial F4/80⁺ cells per field (n = 4, biologically independent samples, 3 ductal areas were randomly selected per each section). d Transwell migration assays of control and CXCR4^Mϕ-cKO macrophages (n = 4, biologically independent samples, 5 microscopic fields were randomly selected from each well). e Heatmap of differentially expressed genes (DEGs) related to macrophage migration from RNA-seq of control and CXCR4^Mϕ-cKO Mϕ. f Transwell migration of CXCR4⁺ and CXCR4⁻ macrophages (n = 3, biologically independent samples, 5 microscopic fields were randomly selected). g Pathway enrichment analysis from DEGs in CXCR4⁺ vs. CXCR4⁻ macrophages, highlighting migration/Chemotaxis pathways ranked by adjusted FDR. h Quantification of Lin^-CD24⁺CD29^Hi Basal/MaSCs (P4) cells (Supplementary Fig. 16a) from control and CXCR4^Mϕ-cKO mammary glands (n = 7, biologically independent samples). i Mammosphere formation of 5000 P4 cells from control and CXCR4^Mϕ-cKO mice (n = 3, biologically independent samples). j Limited dilution assay with P4 cells from control and CXCR4^Mϕ-cKO mammary glands. Table representing serial dilution injections with the corresponding take rate and repopulation frequencies (calculated by ELDA, Pearson’s Chi-squared test, two-sided). k Representative Carmine alum-stained mammary outgrowths. l, m Mammosphere formation assay using 5000 P4 cells cocultured with l 20,000 Mϕ from control and CXCR4^Mϕ-cKO, or m 20,000 CXCR4⁺ and CXCR4⁻ Mϕ (n = 3, biologically independent). n Limited dilution assay of WT P4 injected into control and CXCR4^Mϕ-cKO recipient mice; ductal branching quantified (n = 7, biologically independent samples). o Representative mammary outgrowths. Scale bar, 50 μm in (b) and 25 μm in (k) and (o). Data are mean values  ±  s.d. Statistical significance was calculated by two-tailed unpaired Student’s t-test or one-way ANOVA with Turkey’s test. Box plots show the median (center line), 25th/75th percentiles (box bounds), whiskers extending to 1.5× IQR, and outliers plotted individually. Source data are provided as a Source Data file.