Figure 2.

Cell speed is associated with elevated plithotaxis. (a) The measured properties. Speed, t, t+Δt denote consecutive time points. Anisotropy, (σ_max − σ_min)/2. Strain rate, local spatial derivative of speed in the direction of cell motion (denoted x). Three adjacent cells in the monolayer are depicted with velocities v1, v2, and v3 at similar directions. Assuming that cells maintain cohesiveness, |v1| ≈ |v2| > |v3| imply that the middle cells are deformed in the direction of motion. This is an implicit measure of cell stretching. Stress magnitude, $\sqrt[2]{{\sigma }_{\text{min}}^2+{\sigma }_{\text{max}}^2}$. (b and c) Distributions of ratios between plithotaxis index (b) or geometry index (c) of the top 20% of cells for a given property and the full cell population. (d) Average plithotaxis index as function of the geometry index. (e) Distributions of ratios between the median directionality of the top 20% of cells according to a given property and the full cell population. Median is used because directionality may have extreme values. Note the difference in Y-axis scaling from (b) and (c). (b–e) Accumulated for all N = 4 independent experiments and n = 96 time points per experiment.