GRP and lung cancer: Extensive studies involving EGFR/HER1, HER2, and HER3 in NSCLC cells demonstrate that each of these ErbB s, can be transactivated in a ligand-dependent manner through activation of G protein-coupled receptors (GPCRs) on NSCLC cells, especially by members of the Bombesin (Bn) receptor family (Gastrin-releasing peptide (GRPR/BB2R) and Neuromedin B receptors (NMBR/BB1)), which are present on >75% of lung cancer cell lines [33,37,74,75].