Fig. 3.

Alp- or Car-induced β₁AR-mediated transactivation of EGFR requires GRK phosphorylation. HEK293 cells stably expressing WTβ₁AR (A), or GRK⁻ β₁AR (B) are transfected with FLAG-EGFR and then treated with Dob, Alp, or Car. As indicated, WTβ₁AR induces an increase in phospho-EGFR in response to treatment with Dob, Alp, and Car, whereas GRK⁻ β₁AR lacks this effect. (C) Metabolically labeled HEK293 cells stably expressing PKA⁻ β₁AR are stimulated with various ligands. Alp and Car stimulate a significant increase in β1AR phosphorylation at the GRK sites. Data represent mean ± SE of at least four independent experiments. *, P < 0.05 vs. NS; †, P < 0.01 vs. NS; ‡, P < 0.001 vs. ICI or NS.