Fig. 6. Mechanical stimulation, `stretch', induces Ca²⁺ responses and Ca²⁺ waves. Subepithelial fibroblasts were cultured on elastic chambers made by thin silicone elastomer membrane coated with collagen, and stretched using a stretch machine. Stretch stimulation (12% for 3 seconds) was applied to vertical direction in the figures between 0 seconds and 5 seconds. Ca²⁺ increases in the cells, measured by indo-1 fluorescence, occurred under the presence (A) and the absence (B) of extracellular Ca²⁺. Wave-like Ca²⁺ responses were also observed in the process (see supplementary material Movie 3). Here, each image was a merged RGB color image of F405 (as red), F480 (as green) and F405/F480 (as blue). The scale for Ca²⁺ increase is shown in the right color bar.