Blocked negative selection of developing T cells in mice expressing the baculovirus p35 caspase inhibitor. We have purified two phospholipase A2 inhibitory proteins (Annexin A1) from peritoneal fluid of dexamethasone-treated rats. Dexamethasone induces the synthesis of a phospholipase A2-inhibitory protein (PLIP) of molecular weight approximately equal to 55,000 from calf thymus and PLIPs of molecular weights 55,000, 40,000, 28,000, and 15,000 from A/J mouse thymus and from 12-day embryonic B10.