Complement activation also leads to tumor cell opsonization by C3-derived opsonins (C3b, iC3b, and C3dg), which bind to the CR3/CR4 complement receptors on phagocytes (neutrophils and macrophages) and augment the FcγR-dependent phagocytic uptake of opsonized tumor cells. This evidence concerns the gene CRIPTOP4 and neoplasm.