CXCR7 participates with CXCR4 in CXCL12-induced cyclin overexpression in PB CD34⁺cells. (A) CD34⁺ cells corresponding to a pool of 9 to 19 normal PB samples were stimulated 24 hours in a serum- and cytokine-free medium in the presence or absence of CXCL12 (0.5 ng/mL) and supplemented with AMD3100, blocking anti-CXCR4 and/or -CXCR7 (11G8) antibodies or isotype control for mRNA expression. The cyclinD1, D3, and E1, and cyclin-dependent kinase inhibitor p27 mRNA levels were quantified by quantitative RT polymerase chain reaction and compared with control conditions. Modulations are normalized on the TBP housekeeping gene by a relative quantification and expressed as a box and whisker plot. Deltas indicate significance between experimental conditions (ΔP ≤ .05, ΔΔP ≤ .01). (B) PB CD34⁺ cells were stimulated for 48 hours in a serum- and cytokine-free StemαA medium in the presence or absence (CT) of CXCL12 (0.5 ng/mL), blocking anti-CXCR4 and/or -CXCR7 (11G8) antibodies or isotype control, or (C) CCX704, CCX771, or CCX733 compounds. After cyclin D3/PI labeling, the percentages of cyclin D3–expressing cells in G₀/G₁ or S+G₂/M phases were determined by flow cytometry. Dot plots show the results from 1 representative experiment (n = 3-4). Histograms show the modulations of the percentages of cyclin D3–expressing cells in G₀/G₁ or S+G₂/M phases vs control cells as the mean of fold changes ± SD. *Significance vs control cells (P ≤ .05). Deltas indicate significance between conditions (ΔP ≤ .05, ΔΔP ≤ .01).