BCL-2 proteins are key regulators of programmed cell death. The interplay between pro and antiapoptotic BCL-2 members has important roles in many cancers. In addition to their apoptotic function, recent evidence supports key nonapoptotic roles for several BCL-2 proteins. We used an unbiased lipidomics strategy to reveal that the proapoptotic proteins BAX, and to a lesser extent BAK, regulate the cellular inflammatory response by mediating COX-2 expression and prostaglandin biosynthesis. COX-2 upregulation in response to the bacterial endotoxin lipopolysaccharide is blunted in the absence of BAX, and Bax(-/-) mouse embryonic fibroblasts display altered kinetics of NFκB and MAPK signaling following endotoxin treatment. Our approach uncovers a novel, nonapoptotic function for BAX in regulation of the cellular inflammatory response and suggests that inflammation and apoptosis are more tightly connected than previously anticipated.