Fig. 5. Mechanical properties of cells with and without KT at early stages of cell spreading. The indentation measurements were performed on cells spreading 10-30 minutes after they settled on the substratum. The first point of contact on the cell made by a vertical cylindrical tip as well as the initial distance of the tip from the substratum were observed by indentation on the cell and the substrate next to the cell. The difference between them is the cell height shown in A. As we observed fixed cells by microscopy (Fig. 4), the heights of live cells treated with KT are significantly reduced (P<0.05) compared with those of control cells (A). Force responses to indentation by the cylindrical tip were plotted against % indentation (B). The data represent averaged values and standard errors of 25 and 15 cells with and without KT, respectively. The curve has an indentation phase (loading) indicated by a solid arrow and a retraction phase (unloading) indicated by a dotted arrow. The indentation phase force responses showed a significant reduction of stiffness in KT-treated cells compared with the control. The retraction phase for control cells showed no significant change in KT-treated cells (B).

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