TEK (TEK receptor tyrosine kinase): TEK, also known as TIE2, is a receptor tyrosine kinase mainly found in endothelial cells. It plays a vital role in angiogenesis and maintaining the integrity of blood vessels. TEK signaling is crucial for vascular development and is involved in several vascular diseases, including venous malformations and angiosarcoma. Its function in angiogenesis also makes it a target for cancer treatment, particularly in tumors where new blood vessel formation is a key factor for growth and metastasis.