Figure 1.

EGFR transactivation by GPCRs and cytokine receptors. Various signalling stimuli induce EGFR tyrosine phosphorylation to activate different downstream signalling pathways. Apart from the activation of the classical Ras-MAP kinase pathway, GPCR-EGFR cross-talk is critical for G-protein-mediated stress fibre formation, ion channel modulation or PI-3K-stimulated phospholipid turnover. In contrast to cytokine-induced EGFR tyrosine phosphorylation by janus kinase (Jak)2, GPCR-induced EGFR transactivation is dependent on the intrinsic kinase activity of the receptor, and several cytoplasmic mediators have been controversially discussed in the literature.