Movie S4.

Cell migrating under 1600 Pa compressive load and 0.5% agarose gel. An aggregation competent Ax2 cell expressing ABD-GFP as a reporter for F-actin, is chemotaxing to cyclic-AMP under 0.5% agarose and a compressive load of 1600 Pa. The cell typically projects numerous blebs (indicated by *) with a drastic decrease in the migratory speed. The blebs typically form all around the cells with a noticeable change in the cell shape. Taken by a laser scanning confocal microscope (Zeiss 780) at 2 frames per second about 8-10 minutes after the load is applied.