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. 1999 Aug 2;190(3):375–384. doi: 10.1084/jem.190.3.375

Figure 5.

Figure 5

CD28-mediated activation of c-fos requires the SH3 domain of Lck and cannot be reconstituted by Fyn. (A) Reconstitution of Lck-deficient Jurkat cells with wild-type Lck rescues CD28 stimulation of the c-fos reporter. Wild-type mCD28 was cotransfected with the c-fos reporter plasmid into JCaM1.6 cells stably transfected with Lck. Experiments were performed as described for Fig. 3 A. (B) Lck-deficient Jurkat cells reconstituted with Lck SH3 point mutants (W97A) do not allow CD28 to drive the c-fos reporter. Wild-type mCD28 was cotransfected with the c-fos reporter plasmid into JCaM1.6 cells stably transfected with Lck W97A SH3 mutant. Experiments were performed as for Fig. 3 A. In this experiment, PMA stimulation of the fos-luciferase (fos-luc) reporter was used to control transfection efficiency. (C) Overexpression of Fyn in Lck-deficient Jurkat cells cannot reconstitute CD28 c-fos induction. JCaM1.6 cells stably overexpressing wild-type Fyn were transiently cotransfected with the c-fos reporter as in Fig. 3 A. In this experiment, PMA stimulation of the fos-luciferase reporter was used to control transfection efficiency. All data are representative of three independent trials.