FIG. 6.

EGF-stimulated FLNa Ser²¹⁵² phosphorylation is enhanced by wild-type RSK and antagonized by kinase-inactive RSK. (A) HEK 293E cells were cotransfected with myc-tagged FLNa-WT and RSK-WT (WT), RSK-K112/464R (K/R), or empty vector (none). Cells were starved, labeled with ³²P_i, and stimulated with 50 ng of EGF ml⁻¹ (+) that had been pretreated with 10 μM UO126 (+) or not pretreated with UO126 (−) as indicated. Lysates were prepared, and overexpressed FLNa was immunoprecipitated using myc antibodies. Samples were analyzed by SDS-PAGE and autoradiography. (B) HEK 293E cells were cotransfected with myc-tagged FLNa-WT and RSK-WT (WT), RSK-K112/464R (K/R), or empty vector (none). After EGF stimulation and cell lysis, samples were analyzed by Western blotting using phospho-Ser²¹⁵²-FLNa (p-FLNa), total FLNa, and RSK-C3 antibodies.