FIGURE 2.

Filamin is required for optimal activation of the signal transduction network in response to acute stimulation with shear flow. (A–C) Activation of Ras, which reflects activation of the signal transduction network, was measured by the relocalization of RBD-GFP from the cytosol to the cell cortex. fln^– cells expressing RBD-GFP and either mCherry-tagged ddFLN or empty vector were imaged every 3 s by epifluorescence microscopy with a GFP filter set under 630X magnification with oil immersion. Shear flow was applied at time 0 for 2 s. The shear stress delivered to the cells was 45 dyn/cm² (A), 23 dyn/cm² (B), or 12 dyn/cm² (C). Data is displayed as mean ± SE. Number of cells analyzed is provided in the key and was pooled from four (A) or three (B, C) independent experiments. (D) RBD-GFP response values for individual cells from panels (A–C) at the 6 s time point. Horizontal lines with error bars correspond to mean ± SE. A line at the RBD-GFP response value of 1.0 is shown as a reference to indicate basal levels at time 0. *P < 0.05, **P < 0.01, and ***P < 0.001.