Model of VEGF regulation by sVEGFR-1 and MMP-7 around endothelial cells. (A) Human endothelial cells secrete sVEGFR-1 and block the access of VEGF to its receptor in the normal state. (B) MMP-7 liberates VEGF by degradation of sVEGFR-1. This initiates VEGF-dependent angiogenesis, which leads to a shift toward a proangiogenic state.