The PathScan^® Phospho-HER2/ErbB2 (panTyr) Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of tyrosine-phosphorylated HER2/ErbB2 protein. A HER2/ErbB2 rabbit mAb has been coated on the microwells. After incubation with cell lysates, HER2/ErbB2 protein (phospho and nonphospho) is captured by the coated antibody. Following extensive washing, a phospho-tyrosine mouse detection antibody is added to detect captured tyrosine-phosphorylated HER2/ErbB2 protein. Anti-mouse IgG, HRP-linked antibody is then used to recognize the bound detection antibody. HRP substrate, TMB, is added to develop color. The magnitude of the absorbance for this developed color is proportional to the quantity of HER2/ErbB2 protein phosphorylated on tyrosine.

*Antibodies in this kit are custom formulations specific to kit.

PathScan^® Phospho-HER2/ErbB2 (panTyr) Sandwich ELISA Kit #7968 detects endogenous levels of HER2/ErbB2 protein only when phosphorylated at Tyr residues (see Figure 1). The kit sensitivity is shown in Figure 2. This kit does not cross-react with other proteins of ErbB family (data not shown). This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.

The ErbB2 (HER2) proto-oncogene encodes a 185 kDa transmembrane, receptor-like glycoprotein with intrinsic tyrosine kinase activity (1). While ErbB2 lacks an identified ligand, ErbB2 kinase activity can be activated in the absence of a ligand when overexpressed and through heteromeric associations with other ErbB family members (2). Amplification of the ErbB2 gene and overexpression of its product are detected in almost 40% of human breast cancers (3). Binding of the c-Cbl ubiquitin ligase to ErbB2 at Tyr1112 leads to ErbB2 poly-ubiquitination and enhances degradation of this kinase (4). ErbB2 is a key therapeutic target in the treatment of breast cancer and other carcinomas and targeting the regulation of ErbB2 degradation by the c-Cbl-regulated proteolytic pathway is one potential therapeutic strategy. Phosphorylation of the kinase domain residue Tyr877 of ErbB2 (homologous to Tyr416 of pp60c-Src) may be involved in regulating ErbB2 biological activity. The major autophosphorylation sites in ErbB2 are Tyr1248 and Tyr1221/1222; phosphorylation of these sites couples ErbB2 to the Ras-Raf-MAP kinase signal transduction pathway (1,5).