ERBB2 and cancer: HER2 activation results in the upregulation of several oncogenic downstream pathways, including the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT), RAS/RAF, and mitogen-activated protein kinase (MAPK) (Fig. 1), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), etc., which promote cancer aggressiveness [13,14,40].