ERBB2 and neoplasm: Overexpression of HER2 allows for the constitutive activation of multiple downstream signaling molecules involved in tumor proliferation and survival, including mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K/AKT), phospholipase C γ, protein kinase C (PKC) and signal transducer and activator of transcription (STAT), and thus serves as an oncogenic driver in breast cancer [1].