TEK (TEK receptor tyrosine kinase): TEK, also known as TIE2, is a receptor tyrosine kinase predominantly expressed in endothelial cells. It plays a vital role in angiogenesis and the maintenance of blood vessel integrity. TEK signalling is crucial for vascular development and has been linked to various vascular diseases, including venous malformations and angiosarcoma. Its role in angiogenesis also renders it a target for cancer therapy, particularly in tumours where the formation of new blood vessels is a key factor for growth and metastasis.