However, no bad guy is all bad, and no good guy is all good. For example, Ang-1 has been linked to the development of pulmonary hypertension [174] . Also, under certain circumstances Ang-2 can act as a Tie2 agonist and exert effects similar to those of Ang-1 -an unexplained finding that illustrates our limited understanding of the Ang/Tie system [75] . Complete blockade of Ang-2 might also hamper innate immunity and revascularization.