ERBB2 and cancer: Examples of these approaches are DARPin_9-29 (which binds to a HER2 extracellular region different to the pertuzumab epitope) coupled with gold nanorods, which can reduce in vivo HER2 tumor growth [203]; or the ZHER2:2891 affibody conjugated with 5-Fluorouracil, which is effective in killing HER2 cancer cells [204].