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. 2019 Sep 17;117(8):1405–1418. doi: 10.1016/j.bpj.2019.09.012

Figure 1.

Figure 1

Comparisons of topography, 3D structure, and elasticity of HeLa cells before and after point loading. (A and B) AFM scanning within a 15 × 15 μm region was first performed on the top of the nucleus, and AFM tip was then point loaded near the center of the region at 5 nN for 3 min (shortly, 5 nN/3 min) (A). After loading, the scanning at the same region was performed again (B). (C and D) The first AFM scanning was performed from the top of the nucleus, and then the second scan followed at the same region with no pause. The first three columns showed typical topography of the scanned region, 3D height mapping, and Young’s modulus E mapped to 3D height images, respectively. (A4) and (C4) in the fourth column show representative E distributions before (brown) and after (black) the 3-min point loading (A4) or two sequential scannings (C4). The rule of extracting and computing E was interpreted in (B1), and more details can be seen in Data Analysis, in which E ± SD for each ring (n = 260–4600 from R1 to R10) was plotted. (B4) and (D4) in the fourth column depict the ratio of E before (named E1)/after (named E2) point loading (B4) or two sequential scannings (D4). Here, each line represented the data of one cell with E2/E1 > 1 in blue, ∼1 in red, and <1 in green. E2/E1 = 1 in horizontal dashed lines was used for reference. All data were from two to three repeats. L Ctl, loading control; NL Ctl, nonloading control. To see this figure in color, go online.