KRT7 and neoplasm: The markers cytokeratin CAM 5.2, gross cystic disease fluid protein-15 (GCDFP15), Wilms’ tumor antigen-1 (WT1), mammaglobin 1, and cytokeratin 7 (CK-7), which were used by Sánchez-Serrano et al. [23] and Rosendahl et al. [6], were excluded, as they are not expressed at the cell surface and therefore not suitable as a target for tumor-specific imaging.