Figure 4A,B show the transversal and coronal images of a representative mouse scanned at 1, 5, and 7 days post-injection of 89Zr-DFO-pertuzumab. At 7 days post-injection, JIMT-1 tumor uptake of 89Zr-DFO-pertuzumab was greatly higher than MDA-MB-231 tumor uptake at 7 days post-injection. These results suggest that 89Zr-DFO-pertuzumab as an immuno-PET imaging agent has the potential role for noninvasive and quantitative in vivo imaging of HER2 expression in breast cancer xenografted models. Here, ERBB2 is linked to breast cancer.