The α5β1 integrin is a cell surface receptor that mediates adhesion to fibronectin in the extracellular matrix. It plays a critical role in endothelial cell survival, migration, and proliferation during angiogenesis. By blocking the interaction between α5β1 and fibronectin, volociximab disrupts the signaling pathways necessary for tumor angiogenesis, thereby starving tumors of oxygen and nutrients.