ERBB2 and neoplasm: Due to their beneficial properties, proteins, antibodies, and aptamers could be used as theranostic tools that bind to molecules that are present in excess in tumor cells or their environment, for example, insulin-like growth factor 1 receptor (IGF1R), folate receptor (FR), epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor (VEGF), and integrins [109].