Subsequent SPECT imaging experiments using mice bearing subcutaneous, bilateral MDA-MB-361 (HER2-positive) and MDA-MB-231 (HER2-negative) breast cancer xenografts illustrated that the site-specifically labeled [111In]DOTA-trastuzumab specifically targeted the HER2-expressing xenografts but did not offer a significant improvement over an [111In]DOTA-trastuzumab construct synthesized using a traditional, nonsite-specific conjugation method [90]. Here, ERBB2 is linked to breast cancer.