Pro- and anti-inflammatory actions of OPN in cell injury and infection. The left side of the diagram summarizes proinflammatory and anti-inflammatory events believed to be regulated by OPN. The right side summarizes known or predicted events in the OPN-null mouse. The center illustrates the wounding of the epithelium or endothelium, which is followed by macrophage-mediated containment of an infecting agent and, finally, repair of the injury. MMP-2, matrix metalloproteinase 2; M, macrophage. See text for further details.