Western blot of mouse hippocampal lysate showing specific immunolabeling of the ~68kD PAK1 protein phosphorylated at Thr84 in the first lane (-) using 397158. Phosphospecificity is shown in the second lane (+) where the immunolabeling is completely eliminated by lysate treatment with lambda phosphatase (λ-Ptase , 800 units/1mg protein for 30 minutes).