The bombesin receptor family is a member of the G protein-coupled receptor superfamily and consists of three subtypes of receptors: BB1 (neuromedin B receptor), BB2 (gastrin-releasing peptide receptor), and BB3. These receptors are widely distributed in mammals especially in the CNS and gastrointestinal tract and have numerous effects both physiologically and in pathologic processes including having an autocrine growth action on normal tissues and tumors; potent CNS effects (satiety, circadian rhythm, various behaviors); and potent effects in the immune, gastrointestinal, respiratory and urogenital systems. BB3 is an orphan receptor, with a high degree of homology to the BB1 and BB2 receptors, but has an unknown natural ligand because it has low affinity for all naturally occurring bombesin-related peptides. Interaction of ligand and BB3 activates the Gαq/11 pathway and increase the intracellular calcium concentration. GenScript's BB3-expressing stable cell line was made in CHO-K1 host cell and optimized for calcium assays.