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. 2010 Sep 24;285(48):37650–37662. doi: 10.1074/jbc.M110.138818

FIGURE 5.

FIGURE 5.

PMA- and EGF-stimulated phosphorylation of β4 at Ser-1364 but not Ser-1356 is dependent on RSK1/2 activation. A, PA-JEB/β4 keratinocytes, starved overnight in growth factor-free medium and pretreated for 1 h with the RSK1/2 inhibitor BI-D1870 or the PKC inhibitor Gö6983, were left unstimulated or stimulated with PMA or EGF for 10 min. Cell lysates were analyzed by immunoblotting with antibodies specific to phosphorylated β4 (Ser-1356 and Ser-1364), total β4, phospho-pan PKC (γ Thr-514), phospho-ERK1/2, total ERK1/2, and phospho-p90RSK1. B, COS-7 cells, transiently expressing β4 alone or together with RSK1, RSK2 or a dominant-negative version of these kinase, were starved overnight in growth factor-free medium, and then left unstimulated or stimulated with PMA for 10 min. Phosphorylated β4 (Ser-1356 and Ser-1364), total β4, phospho-RSK1/2, and ERK1/2 were detected by immunoblotting.