EGF-stimulated phosphorylation of β4 at T1736 is mediated by RSK1.

<p><i>A</i>. PA-JEB/β4 keratinocytes, transiently overexpressing RSK1, RSK2, kinase-dead RSK1 or kinase-dead RSK2, were deprived of growth factors overnight and stimulated with EGF or left unstimulated. The cell lysates were analysed by immunoblotting with antibodies as indicated. <i>B</i>. PA-JEB/β4 keratinocytes transfected with RSK1 and/or RSK2 siRNAs were deprived of growth factors overnight and stimulated with EGF or left unstimulated. The cell lysates were analysed by immunoblotting with the indicated antibodies. The values below the blots indicate the signal intensities for the phosphorylated β4-T1736 and β4-S1364 proteins after normalization to the level of α-tubulin.