FIGURE 2:

Surfaces with ridges induce actin fluorescence intensity oscillations. (A) A representative EGFP-actin A20 B-cell on a surface with a 5-µm ridge spacing exhibiting repeated actin fluorescence intensity oscillations. The yellow ROI is centered between two ridges. Scale bar: 5 µm. (B) A representative EGFP-actin A20 B-cell on a flat surface does not exhibit actin fluorescence intensity oscillations. (C) Representative examples of actin fluorescence intensity dynamics, within a square ROI of 5-µm diagonal length, on surfaces with a 5-μm ridge spacing. All traces in C, D, and J were mean-subtracted and normalized by the maximum peak-to-peak intensity of the trace in the top panel in C. (D) Representative examples of actin fluorescence intensity dynamics, within a square ROI of 5-µm diagonal length, on flat substrates. (E) Composite power spectrum of actin fluorescence intensity oscillations for nine cells on substrates with a 3-µm ridge spacing (solid black trace) and nine cells on flat substrates (red trace). The green line denotes the peak at 0.020 Hz. The light gray and light red traces indicate the 99% confidence interval for the cell on the patterned surface and the flat surface, respectively. (F) Same as in E but for a 5-μm ridge spacing. (G) Coefficient of variation (CV) of actin dynamics on flat substrates and on ridged substrates with 5- and 3-µm spacings (p < 0.001 KS test N = 21 cells on ridged, N = 16 cells on flat). (H) EGFP-Lifeact primary B-cell exhibiting actin oscillations on a surface with a 5-µm ridge spacing. Scale bar: 5 µm. (I) Representative example of integrated actin fluorescence intensity levels for a primary B-cell on a substrate with a 5-µm ridge spacing. (J) Composite power spectrum of actin fluorescence intensity oscillations for primary cells (N = 9) on substrates with 5-µm ridge spacing. (K) CV for EGFP-Lifeact primary B-cells on flat substrates and on substrates with 5- and 3-µm ridge spacings (p = 0.0012 KS test, N = 16 cells ridged, N = 22 cells flat).