ErbB3 also known as HER3 is a member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases. ErbB3 is predominantly located on the cell membrane where ErbB3 plays a pivotal role in cellular signaling pathways that regulate cell growth, differentiation, and survival. Structurally, ErbB3 consists of an extracellular ligand-binding domain, a single transmembrane region, and an intracellular domain rich in tyrosine residues essential for downstream signaling. Post-translational modifications, particularly phosphorylation of specific tyrosine residues within the cytoplasmic domain, are crucial for ErbB3′s function. These phosphorylations create binding sites for signaling molecules such as the p85 subunit of phosphoinositide 3-kinase (PI3K), thereby activating the PI3K/Akt pathway, which is vital for promoting oncogenic processes including tumor growth and resistance to apoptosis.