Figure 3 shows that the nanoparticles bound preferentially to HER2+ breast cancer cells (BT474) compared to HER2- breast cancer cells (MDA-MB-231). This agrees with our previous report that the trastuzumab-conjugated MSNPs were preferentially taken up by HER2+ cells over HER2- cells [8]. The gene discussed is ERBB2; the disease is breast cancer.