Concentration-distance profiles of ligand at high cell density.

<p>Ligand profiles computed as a function of distance at high cell density () and nM for s (A) and s (B). These profiles are defined in the extracellular medium () and distance is measured in the radial direction from the cell surface, i.e. . The 2D plots (not shown) viewed from the cell surface appear blue-red in (A) and red-blue in (B).