Figure 4.

Rac1-IQGAP1 interaction is enhanced upon activation of Rac1 by Tiam1. (A) Graph representing normalized IQGAP1 SILAC ratios relative to NIH3T3 cells expressing SF-Rac1 alone from 2 SILAC and 2 reverse SILAC SF-TAP screens (Exp1 and Exp2). Dashed lines represent the upper (red line) and lower (blue line) bounds of the cut-off applied to infer changes in Rac1 binding. (B) StrepII-FLAG Tandem Affinity Purification (SF-TAP) of SF-Rac1 from NIH3T3 cells treated with ethanol (- dox) or 1 μg ml⁻¹ doxycycline (+ dox) to induce expression of SF Rac1 alone (control) or together with the indicated GEFs. Co-precipitated endogenous IQGAP1 and RhoGDI1 were detected by protein gel blot analysis. α-Tubulin was used as a loading control.