FIG. 3.
The PAK1-Cdc42 interaction is dependent on the PIX-binding site in PAK. (A) MDA-MB-231 cells coinjected with WT or a PIX-binding-deficient mutant of GFP-PAK1 (R193G/P194A) and Cdc42-HA. The cells were stained with anti-HA-Cy3 and multiphoton FLIM was undertaken as described in the legend to Fig. 2A. (B) Cumulative FRET efficiency histogram compiled from all the data sets (n = 6) for each plasmid combination including data from Fig. 1 (Cdc42 variants). FRET efficiency = 1 − τda/τd, where τda is the pixel-by-pixel fluorescence lifetime of the donor in the presence of acceptor and τd is the average lifetime of the donor in the absence of acceptor (unstained controls).