FIG. 6.

Differential requirements for Ras and Rap1 in transactivation of Elk-1 in CD45ABC⁺ and CD45RO⁺ T cells. CD45ABC⁺ (open) and CD45RO⁺ (closed) BW cells were transfected with the Elk-1–GAL4–5×GAL4 reporter; cotransfected with 0, 62.5, 125, 250, 500, or 1,000 ng of dominant negative mutant RasN17 (A) or RafN4 (C), with 125, 250, 500, or 1,000 ng of RapGAP (B middle), or with 125, 250, 500, 1,000, or 2,000 ng of RapN17 (B, left and right); and stimulated with an anti-TCR MAb (A, B, and C, left; B, middle) or PMA (A, B, and C, right). The amount of total DNA used for each transfection was adjusted with the matched empty vector control to 1.0 or 2.0 μg, as required. (D) Comparison of the effects of RapN17 on CD45ABC⁺ and CD45RO⁺ cells stimulated with different concentrations of MAb 3D3. Cells were transfected with the Elk-1–GAL4–4×GAL4–luciferase reporter and cotransfected with a single dose of RapN17 or the empty vector control and stimulated with different concentrations of MAb 3D3. The data are expressed as the ratio of the stimulation in cell transfected with RapN17 to the stimulation in cells transfected with the empty vector control. Luciferase activities were normalized against the internal control (pRL-CMV). RLU, relative luciferase units.