Fig. 2

Effects of peptide R on cell proliferation, vitality and migration. a Cell counting of U87MG cells stimulated (+CXCL12) or not (-CXCL12) with 100 ng/ml of CXCL12 and treated with Plerixafor (10 μM) or peptide R (10 μM) for 24, 48 and 72 h. Mean values ± SD of n = 3 independent experiments. **** P = 0.0001, one-way ANOVA, (asterisks represented in the figure). P = 0.0293 (–CXCL12 cells versus peptide R-treated cells), P = 0.0005 (+CXCL12 cells versus peptide-treated U87MG) (72 h of treatments), unpaired two-tailed Student t-test. b MTT assay performed on U87MG cells after 72 h incubation with CXCL12, in the presence of peptide R or Plerixafor, compared to untreated cells (-CXCL12) (means ± SD of n = 3 independent experiments). **** P = 0.0001 (asterisks represented in the figure), one-way ANOVA. P = 0.0148 (-CXCL12 cells versus Plerixafor-treated U87MG), P = 0.0419 (-CXCL12 versus peptide R-exposed cells), P = 0.0084 (+CXCL12 cells versus peptide R-treated U87MG cells), unpaired two-tailed Student t-test. c Quantitative analysis of U87MG cells migration (for details see Methods section) in response to 10 % FBS (black bar) or in response to CXCL12 in the absence or presence of peptide R or Plerixafor. The percentages of area occupied by migrating cells are reported as mean values ± SD (n = 6). **P = 0.0024 (asterisks shown in the figure) one-way ANOVA. P = 0.0425 (+CXCL12 versus + Plerixafor), P = 0.0029 (+CXCL12 versus + peptide R cells), unpaired two-tailed Student t-test. d Scanning electron microscopy (SEM) observations were performed at the end of the 20-hour assays on cells treated as described in (c). Imaging was performed on both the upper (panels a–c) and lower sides (panels d–f) of the filter. Asterisks represent the migration leader elements. Scale bars are indicated