Trastuzumab induces internalization and degradation of HER2overexpressed on HER2-positive breast cancer cells.38 To analyze the potential of anti-HER2 VHH-FcK in HER2 proteindegradation, Western blot analysis was performed using cells (BT-474and BT-474-TR) treated with 20 μg/mL of anti-HER2 VHH-FcK andTrastuzumab as a control (Figure 2e). Here, ERBB2 is linked to breast cancer.