FIG. 8.

(A) COS-7 cells transfected with LckY505F (Y505F) or LckT316 M/Y505F (T316 M/Y505F) were either left untreated or were incubated with PP2 for 2.5 h. Cells were lysed, and equivalent amounts of protein were used in an enzyme-linked immunosorbent assay-based kinase assay. Expression levels of Lck were comparable between transfectants as determined by Western blotting. To determine background kinase activity levels, untransfected COS-7 cells were measured in the same assay. The plotted assay is representative of two separate experiments. Mean values of duplicates are plotted after subtraction of the background activity. (B) COS-7 cells transfected with T316 M/Y505F were treated with GA and PP2 as described for Fig. 7A. Cells were lysed and immunoblotted for Lck.