Anti-erbB4 Antibody, clone HFR1/2G4

v-ErbB was identified as the viral counterpart of the EGF Receptor, and its relatives have adopted this nomenclature (or the HER nomenclature for human proteins). These proteins are activated by Heregulin, Neuregulin and Amphiregulin. ErbB-2/HER-2, also known as neu, is amplified in large numbers of highly aggressive breast cancers, but all the family members are capable of heterodimerization, and together activate downstream signaling pathways. ErbB-3 has a natural "substitution" at the codon which is an invariant Lys residue at the ATP-binding site of all protein kinases. It is therefore inactive as a kinase, and can only become phosphorylated by heterodimerization with another erbB-family member. All members of this family, when Tyr-phosphorylated, can nucleate the formation of signaling complexes through adapter proteins.