Hypo-osmotic perturbation induces an increase in membrane tension. (A) Schematic of tether extraction experiment during a hypo-osmotic perturbation. Arrows and curve, membrane tension. (B) Representative bright-field image of a tether extraction experiment. Bar, 10 µm. (C) Representative tether extraction force curve, with tether forces for 1× and 0.5× Ringer’s indicated. (D) Plot of tether force values for fibroblast cells in 1× (blue box) and 0.5× (red box) Ringer’s. ***, P < 0.001, t test statistics. Blue and red boxes extend from the 25th to 75th percentiles, with a black line at the median and a black cross at the mean; black whiskers extend from 5th to 95th percentiles for both conditions; values outside these ranges are plotted as individual points. Five different paired measurements, among 25 pairs of 1×/0.5× Ringer’s, were chosen to represent the change in tether force observed in C. These paired measurements were correlated using a gray line in the plot.