GRPR and prostate cancer: The radioconjugates [111In]In-DOTA-Tz-TCO-PEG4-AR, [111In]In-DOTAGA-Tz-TCO-PEG4-AR, [111In]In-DOTA-Tz-TCO-Pip-AR and [111In]In-DOTAGA-Tz-TCO-Pip-AR were studied to determine their uptake and internalization in a prostate cancer in vitro model using the well-established GRPR-positive cell line, PC3.