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