receptor kinases
Receptor tyrosine kinases epidermal growth factor receptor EGFR , platelet-derived growth factor receptor PDGFR , vascular endothelial growth factor receptor VEGFR , HER2/neu Receptor tyrosine kinases add phosphate groups to other proteins to activate or inactivate them. Receptor kinases add phosphate groups to receptor proteins at the surface of the cell. These receptor proteins receive signals from outside the cell and initiate a signal transduction process inside the cell. Tyrosine kinases add phosphate groups to tyrosine residues in the target protein. They can cause cancer by turning the receptor permanently on constitutively , even without signals from outside the cell.