Because of its overexpression in many solid tumors, gastrin-releasing peptide receptor (GRPR) represents a promising therapeutic target and imaging marker for cancer. Gastrin-releasing peptide (GRP) and bombesin are the natural ligands for GRPR. To improve in vivo stability, researchers at the University of British Columbia synthesized two 68Ga-labeled GRPR agonists by replacing Val and His sequences in GPR(20-27) and bombesin(7-14) with Tle and NMe-His, respectively.