Fig. 6

Endothelin A2 (Endo II) promotes trastuzumab-induced human epidermal growth factor receptor 2 (HER2) internalization and suppression of HER2-positive cancer cell motility. a Flow cytometry analysis was used to measure effects of trastuzumab (TZ, 84 μg/ml) on HER2 levels in HCC1954 pGIPZ (NT) or Endo II knock-down (KD)1 cells treated for up to 18 hours and stained with phycoerythrin (PE)-anti-HER2. Representative histograms (left) and a graph of changes in mean fluorescent intensity (MFI) of HER2 staining from three experiments are shown (*P < 0.05, **P < 0.01, ***P < 0.001). b HCC1954 pGIPZ NT and Endo II KD cells seeded in a 96-well plate and after 18 hours wound areas were generated in the cell monolayers prior to treatment with or without trastuzumab (84 μg/ml). Following real-time imaging for 24 hours, the extent of cell migration into the wound area was visualized (left, representative images shown) and quantified from triplicate wells (right) for NT controls (upper; **significant difference at endpoint with TZ treatment) and Endo II KD cells (lower; no significant differences at endpoint were observed with TZ treatment)