Correlation of protein recruitment with plasma membrane protrusion velocity. (A) The image shows an HT1080 cell stably expressing GFP-Abi1 and mCherry. The image is split into constituent channels, and the mCherry signal is segmented to construct a cell mask image. Eroded and dilated versions of this mask image are used to construct the region of interest (denoted by the yellow lines) in the GFP-Abi1 image. Bar, 10 µM. (B) Velocity and GFP-Abi1 intensity maps for the cell in A, together with the result of a cross-correlation. (C) Mean cross-correlations of velocity and fluorescence intensity maps reveal a strong correlation between membrane velocity and protein localization in HT1080 cells expressing GFP-Abi1. Correlations between velocity and CellMask or noise were considerably weaker (22 ≥ ncell ≤ 41). (D) Peak values (at Δs = 0 and Δt = 0) in cross-correlations of velocity and fluorescence intensity maps for individual cells (each dot represents a single cell). A one-way analysis of variance (ANOVA) test shows the differences in mean values to be highly significant (P < 0.0001). Error bars represent standard error of the mean.
