Figure 5. Gamma camera–based imaging of xenografted mice, at 6 and 24 hours after injection of 125I-labeled Affibody molecules. In a set of experiments, the first-generation Affibody molecule, ZHER2:4 (A) was compared with the affinity-matured Affibody molecule ZHER2:342 (B) at 6 hours post-injection. Intensity of color corresponds to radioactive accumulation: low (blue) and high (yellow) accumulation. Kidney uptake is more prominent for the ZHER2:4 Affibody molecule (A). The tumor uptake of ZHER2:342 was stable up to at least 24 hours post-injection (C).