GPR110 peptide agonist P12 is a peptide that acts as an agonist for GPR110. This compound markedly enhances the initial rate of G protein GTPγS binding stimulated by GPR110. It mimics the action of the natural ligand, causing the extracellular domain (ECD) of GPR110 to dissociate from the seven-transmembrane domain (7TM) and exposing the N-terminal β-strand-13/stalk region of the 7TM domain, which acts as the agonist activating G protein signaling. GPR110 peptide agonist P12 is applicable in research related to developmental disorders and cancers associated with GPR110.