Receptor Tyrosine Kinases (RTKs) are a class of cell surface receptors that play a crucial role in cellular communication. They are activated by the binding of specific ligands, such as growth factors, which leads to the phosphorylation of tyrosine residues on the receptor itself and on downstream signaling proteins. This process initiates various cellular responses, including growth, differentiation, and metabolism. RTKs are essential in many biological processes and are implicated in various diseases, including cancer. Abnormal activation or mutations in RTKs can lead to uncontrolled cell proliferation. Examples of RTKs include EGFR (Epidermal Growth Factor Receptor) and HER2 (Human Epidermal growth factor Receptor 2), both of which are significant in cancer research and treatment.