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R. Li, N. Mitra, H. Gratkowski, G. Vilaire, R. Litvinov et al., 795-798 FOOTNOTES * We thank Monique Agrapart for providing with HUVEC, Thomas Bader for his help for HTRF experiments and Stefano Marullo for giving pRLuc and pEYFP plasmids We also thank Marie-Camille Delsuc and James Vigneron for preliminary experiments We would like to give our thanks to Stefano Marullo, Catherine Labbé-Jullien, Ralf Jockers and Claudine Mayer for helpful discussions. This work was supported by grants from Association de Recherche contre le Cancer The local Post-Genomic Plat-Form of Pitié- Salpêtrière (P3S) was acknowledged for providing access to the Fusion Packard reader. The local Cellular Imaging Plat-Form of Pitié-Salpêtrière (PICPS) was acknowledged for providing access to the confocal microscope. The abbreviations used are: BRET, Bioluminescence Resonance Energy Transfer; HTRF, homogeneous time-resolved fluorescence; HUVEC, Human Umbilical Vein Endothelial Cells; TM, transmembrane domain of CX3CL1; CD, chemokine domain, from the Institut National de la Santé et de la Recherche Médicale (Programme National De Recherche Sur Les Maladies Cardiovasculaires), from European FP6 contracts " INNOCHEM " (LSHB-CT-2005-518167 to C.C.) without chemokine domain; TM&cyto, CX3CL1 without chemokine domain and mucin stalk; ALA5, CX3CL1 mutant with alanines replacing the 321-325 residues; ALA7, CX3CL1 mutant with alanines replacing the 326-332 residues; ALA12 , CX3CL1 mutant with alanines replacing the 321-332 residues, 2003.

/. D. Luc and . Bret, The linear regression is given and indicates that BRET is constant in this range. E. BRET variation versus CX3CL1-YFP concentration using HEK cells transfected with various amounts of CX3CL1-Luc and CX3CL1-YFP. F. HEK-293 cells were transfected with 0.1 µg CX3CL1-Luc and 0.2 µg CX3CL1-YFP supplemented with 2 µg of empty pcDNA3 (left) or of CX3CL1-pcDNA3 (right). The values are the mean of 15 measurements (± SEM). The difference between the CX3CL1 BRET ratio with or without native CX3CL1 was significant, The CX3CL1 content of each sample was analyzed by western blot to check that the untagged CX3CL1 expression did not change expression of CX3CL1-Luc and CX3CL1-YFP (data not shown), pp.0-0001