CXCL4 Integrins Angiogenesis Figure 7. Immobilized CXCL4 or CXCL4/CTF promotes and soluble CXCL4 or CXCL4/CTF inhibits integrin-dependent endothelial cell migration. A. Soluble CXCL4 or CXCL4/CTF inhibits migration on fibronectin toward VEGF (5 ng/ml). HUVECs migration was determined in the presence or absence of the indicated concentrations of CXCL4 or CXCL4/CTF or CXCL4/CTF-S or 25 mg/ml of RGD-, RGE peptides or 10 mg/ml of anti- integrin antibodies (anti-av; AV1 and anti-a5b1; JBS5) as described in Material and Methods. Relative cell migration is indicated, each value is a mean6SEM from 3 independent experiments. Error bars represent the mean6SD, #, P#0.05; *, P#0.005, **, P#0.001 compared to the number of cell migrated in the absence of CXCL4 or CXCL4/CTF or anti-integrin antibodies or RGD peptides. B. Immobilized CXCL4 or CXCL4/CTF supports HUVECs migration in avb3 and a5b1 integrins-dependent manner. Cell migration assay was performed on immobilized CXCL4 or CXCL4/CTF in serum free medium and in the presence or absence of inhibitory anti-integrin antibodies or RGD-, RGE peptides. The results at each point are the mean cell number of 10 randomly selected high magnification microscopic fields. Error bars represent the mean6SD, *, P#0.005; *, P#0.001 compared to CXCL4 or CXCL4/CTF in the presence of IgG control antibody; n = 3 independent experiments. C. Soluble CXCL4 or CXCL4/CTF inhibits migration on PLoS ONE | www.plosone.org 10 July 2008 | Volume 3 | Issue 7 | e2657