Epidermal growth factor receptor
A431 cells are used in studies of the cell cycle and cancer-associated cell signalling pathways since they express abnormally high levels of the Epidermal growth factor receptor (EGFR). They are often used as a positive control for EGFR expression. They contain no functional p53, a potent tumor suppressor gene, and are highly sensitive to mitogenic stimuli. In xenografts, A431 cells have shown antitumorigenic properties of introduced EGF and related radiation sensitization characteristics. Other "in vitro" studies have found EGF to also cause substantial lowering of DNA replication and protein synthesis. The A431 lines engineered to express tumor antigens such as mesothelin and GPC3 have been made as cell models to test cancer therapeutics.