*2.9. Particle Image Velocimetry (PIV) Measurement*

PIV analysis was performed using a custom algorithm based on MATLAB's PIVlab software package (Matlab2020a, PIVlab2.36). We used live cell image sequences of JAR cells to analyze the direction and magnitude of cell movement. To avoid the influence of the background movement on the calculated results, the calculated velocity field was subtracted from the average velocity. For the velocity vectors arrows, each pixel of length represents 0.05 µm/min.
