Figure 1.

(A) Proliferation of CT26 colon carcinoma cells in supernatants of CT26 cells, either or not supplemented with 100 ng ml⁻¹ recombinant CXCL12, or in supernatants of CT26 cells expressing CXCL12 or the K1R-CXL12 mutant. The supernatants contained either 1 or 10% FCS. Changes in cell numbers were measured by bioluminescence of these luciferase-expressing cells, after the addition of luciferin. Shown are the results of one of the two experiments with virtually identical results. The s.e.m. are extremely small (∼0.02%) and error bars are therefore not shown. For clarity, we used markers that are far larger than the error bars, and they were slightly displaced when overlapping to make them all visible. (B) Verification of effects on CXCR4 by CXCR4-mediated chemotaxis of TAM2D2 T-cell hybridoma cells in 2 h towards different concentrations (ng ml⁻¹) of recombinant CXCL12, towards supernatants (sup) of control CT26 cells or of CXCL12- or K1R-CXCL12-expressing CT26 cells, or to 100 ng ml⁻¹ CXCL12 added to the K1R-CXCL12-containing supernatant. AMD3100 (125 ng ml⁻¹) and TC14012 (1 ng ml⁻¹) inhibit completely at these concentrations, whereas they have no effect on CXCL12-induced proliferation. Shown are the results of one of the four experiments with similar results. (C) FACS analysis of CXCR4 and CXCR7 on CT26 cells grown in vitro and of PI-stained cells, either UV-irradiated or not 16 h before.