Focus issue: understanding mechanisms of inflammation.

This Focus Issue of Science Signaling, which complements the Science Special Issue on Inflammation, includes research that reveals regulators of a receptor implicated in an inflammatory bowel disease, as well as the contribution of a matrix metalloproteinase to skin inflammation. Perspectives discuss the role of proinflammatory cytokines in brain inflammatory disorders and the regulation of multiple types of cell death in tissues in response to proinflammatory factors. Together with content from the Science Signaling Archives, these articles underline the importance of understanding the basis of inflammatory responses that can both protect and harm the host.