Directional motility of cadherin clusters depends on the actin polymerization. (a and b) The calcium-switch assay with EcDnΔ-αABD–expressing cells in the presence of Arp2/3 inhibitor CK548 (a, αCK548) and a low dose (25 nM) of cytochalasin D (b, αCD). The cells immediately before the switch (0) and 5 min after the switch (5) are presented. Time-lapse images of the boxed regions are shown at the bottom of each image pairs (numbers indicate minutes after the switch). Note that both inhibitors did not stop cluster formation but immobilized the clusters. Bars: (main images) 10 µm; (insets) 5 µm. (c) The calcium-switch assay with EcDnΔ-αABD–expressing cells in the presence of a low dose (25 nM) of cytochalasin D. Cells were fixed 5 min after addition of calcium and stained for the chimera (c, α) and actin (c′, actin). Note that clusters (three of them are indicated by arrows) appear in proximity to the remaining F-actin structures. Bars: (main images) 5 µm; (insets) 3 µm.