In addition, it is also reported that Δ16HER2 initiates a key oncogenic signal that has a significant impact on HER2-driven breast cancer stemness (Castiglioni et al., 2006), tumorigenesis (Turpin et al., 2016), and drug resistance (Jackson et al., 2013) as compared to its full-length counterpart. This evidence concerns the gene ERBB2 and breast cancer.