ERBB2 and breast cancer: Compared with the golden standard method of fluorescence in situ hybridization (FISH), the advantages of QD-based IHC have been well documented since Wu et al.[29] labeled HER2 on human BC cells (SK-BR-3) and mouse mammary tumor sections by QD-IgG conjugates for the first time, which was much easier, cheaper, less time-consuming, and could relieve the medical burden, especially for developing countries.