sentences:  CR3 also recognizes iC3b when bound to the surface of foreign cells.iC3b is generated by proteolysis of C3b and binding to the receptor causes phagocytosis and destruction of the foreign cell opsonized with iC3b.CR3 belongs to a family of cell surface receptors known as integrins (because they share this particular β chain, they are referred to as β2-integrins), which are extremely widely distributed throughout nature and which generally are important in cellular adhesion, migration, phagocytosis and other cell-cell interactions in a variety of cells and circumstances.