GRP and cancer: Additionally, GRP acts as a mitogen and proangiogenic factorin different cancers.30 Bombesin (BN) isa 14-amino acid peptide (Pyr-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2) that shares a homologous seven-amino acid C-terminal regionwith GRP.