Movie S3. Polarization of a Tension-Based, Apical Actin Network

(A) Primary keratinocytes were plated for 12 hr in low-calcium medium and then switched to high-calcium medium for 20 hr. The epithelial sheet was then imaged by time-lapse video microscopy for 30 min, focusing either on the apical (left panel) or basal (right panel) plane. Elapsed time is shown at bottom right. Bar represents 10ìm.

(B) Z stack of cells observed in Supplemental Movie S2B, taken at the end of the movie from top to bottom. Note that even at early stage of sheet formation, the actin cytoskeleton becomes polarized.

(C) Cells shown in Figures 4E and 4F were subjected to a top-down Z stack to illustrate the relation between nascent and mature junctions and their association with the actin cytoskeleton. E-cadherin, red; phalloidin, green; Dapi, blue. Bar represents 10 ìm.

Movie S3. Polarization of a Tension-Based, Apical Actin Network(A) Primary keratinocytes were plated for 12 hr in low-calcium medium and then switched to high-calcium medium for 20 hr. The epithel