Lysophosphatidic acid is the simplest phospholipid known. It is produced by platelets, endothelial cells, leukocytes, some cancer cells, astrocytes, and injured fibroblasts. Lysophosphatidic acid is thought to play a role in platelet aggregation and fibrosis. Since in radiation injury, platelet aggregation on endothelial cell surfaces and fibrin formation are the main events, lysophosphatidic acid might play a major role in radiation injury.