GRPR and breast cancer: In vivo studies were conducted using breast cancer cell models, namely T47D (GRPR+/low αvβ3) and MDA-MB-435 (GRPR-/αvβ3+), with 18-F-FB-PEG3-RGD-BBN, 68Ga-NOTA-RGD-BBN, and 64Cu-NOTA-RGD-BBN [97].