ANGPT1 and neoplasm: The angiogenic switch is a rate-limiting step in tumor progression 31 that is associated with a shift in the ratio of the vessel stabilizing angiopoietin-1 (ANGPT1) to the destabilizing factor angiopoietin-2 (ANGPT2) in favor of ANGPT2. Consequently, the angiogenic switch renders the tumor vasculature amenable to vessel sprouting 32.