In the search for anticancer drugs, a promising area involves the design of small-molecule inhibitors of growth factors active in malignancies. PDGF and its receptors are implicated in tumorigenesis and angiogenesis, prompting Sebti and colleagues to design a synthetic molecule, called GFB-111, that binds to PDGF. Their new molecule has four-fold symmetry consisting of four identical peptide loops with negative and hydrophobic residues tailored to complement the specific PDGF surface involved in binding to its receptor, thereby preventing binding. Human tumor-bearing nude mice injected with GFB-111 had significant reduction of both tumor growth and angiogenesis (see p. 1065).