Fig. 7. Diagram of the hypothetical relationship between the spatio-temporal distribution of traction stress and a cycle of movement for each cell type. For each cell type, colored areas represent the average 90th percentile traction stress that is highest for the wild-type (dark blue), intermediate for mlcE^– (light blue) and very low for mhcA^– cells (gray). Periods of development, loss and regeneration of traction stress asymmetry are indicated by horizontal bars. The total number of cycles occurring within a period of observation (3 minutes) is expressed as cycles per minute. Graph illustrating differences in the rate of development (blue), retraction (red) and regeneration (green) of traction stress asymmetry for the wild-type, mlcE^– and mhcA^– cells. The gray line represents a period in which mhcA^– cells lack traction stress asymmetry, except where marked (asterisk).