In vitro, PCSN probes bound to the surface of SK-BR3 cells (human breast cancer cell line, HER2; 3+) within 4 h and were internalized after incubation for 24 h in cell culture medium containing dispersed PCSN probes (PCSN concentration: 1200 ppm) (Figure 3). The gene discussed is ERBB2; the disease is breast cancer.