A therapy should intervene in the right place and at the right time, with the proper duration of action and without collateral damage [156, 157] . The Ang/Tie system is involved in many processes and lies at the intersection of molecular mechanisms of disease. Thus, interventions targeting this system might have benefits. As in other pleiotropic systems, however, unexpected and unwanted side effects are a serious risk. The absence of redundant systems to take over the function of Ang/Tie2 has the advantage that the effect of therapeutic intervention cannot easily be bypassed by the cell. On the other hand, because the cell has no escape, the effect may become uncontrolled and irreversible. Moreover, the exact function of the Ang/Tie system in the pathological cascade is not fully established. What we see in animal models and in patients is most probably the systemic reflection of a local process. We do not know whether this systemic reflection is just a marker of organ injury or even a mediator of distant organ involvement.