Receptor Tyrosine Kinases are Signaling Intermediates of G Protein- Coupled Receptors

G protein-coupled receptors (GPCRs) can utilize receptor tyrosine kinases (RTKs) to mediate important cellular responses such as proliferation, differentiation and survival. Recent advances in the field suggest that GPCRinduced transactivation of RTKs might be important for diseases such as cancer and cardiac hypertrophy. Depending on the receptor and cell type, GPCR signaling involves activation of several different RTKs. By activating different subsets of RTKs, GPCRs can fine-tune their effects on target cells. Furthermore, RTK-independent signaling pathways also initiated by GPCRs may modify the biological read out of the transactivated RTKs. This review focuses on the mechanisms how GPCRs and intracellular messengers elicit transactivation of different RTKs and the resulting different biological responses.