GRPR and prostate carcinoma: The GRPR antagonist [68Ga]Ga-RM2 (RM2=DOTA-4-amino-1-carboxymethylpiperidine-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) has been particularly attractive for prostate cancer imaging.