To understand the underlying mechanism by which Hu1C8 maintains a similar activity of inhibiting cancer cell growth to Hu5F9-G4 but has a low activity to induce hemagglutination, we compared the structure of the Hu1C8-CD47 complex with that of the Hu5F9-CD47 complex (PDB code: 5IWL) (25) and the SIRPα-CD47 complex (PDB code: 2JJS) (26) (Fig. 5F). The gene discussed is CD47; the disease is cancer.