ERBB2 and neoplasm: The activation of the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt) pathways due to HER2 homo- or hetero-dimerisation promotes tumour cell proliferation, differentiation, survival and migration, causing adverse pathological disease and poor prognosis [27,32,33].