GRPR and cancer: The gastrin-releasing peptide receptor (GRPR) (also known as bombesin receptor 2 (BB2)) is a seven-transmembrane receptor and is expressed on the surface of a variety of cancer cells, including breast, colon, lung, pancreatic, and prostate [1,2,3,4,5,6,7], while physiological GRPR expression in healthy tissues is low, with the exception of the pancreas [8].