GRPR and prostate carcinoma: Confocal microscopy revealed that these structures were efficiently internalized in vitro in GRPR-positive PC-3 and DU-145 cells, but not in GRPR-negative 293T cells; high uptake in prostate cancer cells was mediated by receptor–ligand interaction, as proven by increased Ca2+ release upon incubation of cells with receptor-activating ELP-GRP micelles.