It has been known that Ang1 and Ang2 bind to their common receptor Tie2, antagonize each other and control blood vessel maturation and stabilization [52]; Ang1 stabilizes blood vessel formation [3,52–54], whereas Ang2 destabilizes the blood vessel structure and increases vascular permeability in lung injury [12,13,55–57], tumors [39–41] and lung fibrosis [58,59]. Here, TEK is linked to pulmonary fibrosis.