G protein-coupled receptors (GPCRs), which represent the largest membrane protein family, are cell surface receptors that transmit extracellular stimuli to intracellular signaling. GPCRs activate intracellular signal pathways through their associated G proteins. They recognize various ligands such as hormones, neurotransmitters, inflammatory mediators, nucleic acids, peptides, amino acids, lipids, and light.

Nearly 800 GPCRs have been identified in humans so far. Many GPCRs contain mutations or polymorphisms that are associated with a variety of diseases and disorders. Nearly 40% of all marketed drugs are known to act through GPCRs and more than 30% of the new drugs in development are targeting GPCRs. Despite the fact that GPCRs form  the largest superfamily of cell surface receptors involved in signal transmission, in clinical practice only few anticancer compounds are currently used in order to interfere with GPCR-mediated signaling. GPCRs control many aspects of  cancer progression including tumor growth, invasion, migration, survival and metastasis supporting the importance of blockade of this pathway.