(A, B) The 293 cells were transfected with the following plasmids expressing HA-tagged WT-Rac1, L61-Rac1, N17-Rac1, or WT-Rac1+SOD1. HA-Rac1 was then immunoprecipitated from the 293 cell lysates by using an anti-HA antibody, and the proteins that associated with Rac1 were separated by SDS-PAGE and characterized by Western blotting with the indicated antibodies. In a similar set of experiments, association of endogenous Rac2 with MKK6 was assessed in RAW cells infected with Ad.LacZ or Ad.SOD1. Cell lysate from each condition was immunoprecipitated with anti-Rac2 antibody and evaluated with Western blot. (C)
In vitro association of purified GST-CA-MKK6 and GST-WT-MKK6 with His-tagged Rac1. His-tagged Rac1 was immobilized on Dynabeads, and pull-down assays were performed with an equal amount of purified CA or WT GST-MKK6. Proteins bound to Rac1 were evaluated with Western blot by using anti-GST and anti-Rac1 antibodies. All panels are representative for n = 2–5 independent experiments as indicated.