Random and directional migration of cells that are periodically protruding. (A) Random migration of rounded CHO cells plated on serum-coated glass under agar with intact microtubules. Yellow outlines show cell position at the beginning of recording and arrows denote the direction and net migration distance. The mean speed was 0.53 ± 0.15 µm/min. (B) Bar graph representing the distribution of cell directions within 1-h migration of CHO cells under agar with “0” indicating the direction along the X axis. The plot was calculated from two separate recordings for a single experiment out of two repeats (n = 65 cells). (C) Migration of NIH 3T3 cells under agar with chemoattractant (200 ng/ml PDGF) presented in a distal well in the agar gel. Green arrows point in the direction of the chemoattractant source. The initial position of the cells is outlined in yellow and red, where yellow outlines indicate cells moving in an amoeboid-like fashion and red outlines indicate cells migrating mesenchymally. Mean speed of amoeboid-like cells was 0.55 ± 0.14 µm/min. (D) Bar graph representing the distribution of cell directions 1 h after plating under agar with “0” indicating the direction toward to the well containing chemoattractant. The plot was calculated for n = 51 cells from three separate experiments.