ErbB2 also known as HER2, CD340, Neu is a member of the epidermal growth factor (EGF) receptor family of receptor tyrosine kinases, which consists of receptor tyrosine kinases that play critical roles in cell signaling pathways related to growth and differentiation. ErbB2 is primarily located on the cell membrane, where binding with ligands can form homodimers or heterodimers with other EGFR family members, such as ErbB3. This dimerization activates downstream signaling cascades, including the phosphoinositide 3-kinase pathway, which regulates cell proliferation, survival, and motility. Aberrant expression of ErbB2 is associated with various cancers, particularly breast carcinoma, where amplification or overexpression occurs in 20-30% of cases, making ErbB2 a significant biomarker for disease prognosis and a potential target for therapeutic interventions.