EGF-R Cellular Phosphorylation Assay (intracellular kinase activity assay) for compound screening and profiling in intact cells
Epidermal growth factor receptor (EGF-R) is a 179kDa membrane-bound glycoprotein expressed on the surface of epithelial cells. EGF-R is a member of the growth factor receptor family of protein tyrosine kinases. Ligand dependent receptor activation results in autophosphorylation of the receptor’s intracellular kinase domain. Genetic alterations which impact upon the activation level of EGF-R, result in cell proliferation. Therefore, this process is responsible for cellular transformation and makes EGF-R a preferred cancer-related therapeutic target.
EGF-R, ERBB, mENA, ERBB1
The human epidermoid carcinoma cell line (A431) is known to overexpress EGF-R. Stimulation of these cells with its physiological ligand human epidermal growth factor (EGF), results in a robust receptor autophosphorylation. Compounds are preincubated before cell stimulation to allow thorough target binding. Stimulation conditions are optimized to determine dose-related inhibition of the phospho-EGF-R signal, which is subsequently quantified by Sandwich-ELISA technique. The assay is validated based on known inhibitors of EGF-R kinase activity (see Fig.1).
Substrate phosphorylation as a readout of intracellular kinase activity via ELISA
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Reference compound IC50 for EGF-R
Lapatinib is known to inhibit the EGF-induced phospho-EGF-R signal in a specific manner. The compound was included for the validation process and the cellular EGF-R assay generated highly reproducible IC50 values. The graph shows a representative result.