The corresponding Raman spectra (averaged over the areas indicated in Figure 4G) documented that those different levels of HER2 expression are also represented, at dramatically differing intensity levels of the Raman spectra, with a higher intensity for the HER2 high-expressing simulated breast cancer metastasis (red spectrum) and a lower intensity for the HER2 low-expressing counterpart (blue spectrum) (Figure 4I). Here, ERBB2 is linked to breast carcinoma.