Fig. 3. Effect of Ang-1 and Ang-2 on chemotaxis of MPC in a Boyden chamber assay in which PDGF-BB was used as positive control. (A) Ang-1 (0.67 µg ml^-1) and Ang-2 (0.67 µg ml^-1) used alone or in combination stimulated the migration of MPCs. The stimulatory effect obtained with the Ang-1/Ang-2 combination was higher than but not significantly different from that obtained with the single molecules. Bars represent the SEM (n=6). ^*, P<0.0001; ^**, P<0.02; ^***, P<0.03. (B) Ang-1-mediated stimulation of MPC migration (0.67 µg ml^-1) was inhibited by soluble Tie2 (13.4 µg ml^-1). Cells were responsive to the PDGF-BB positive control and showed no random migration (chemokinesis) when Ang-1 (0.67 µg ml^-1) was loaded in both the upper and lower compartments of the Boyden chamber. Bars represent the SEM (n=6). ^*, P<0.001; ^**, P<0.01; ^***, P<0.05. Values are expressed as optical density (O.D.) in both A and B.