Annexin A2 (ANXA2),also named Annexin-2 or Lipocortin II,is a Ca2+ binding protein that is up-regulated in virally transformed cell lines and human tumors. This calcium-regulated membrane-binding protein,whose affinity for calcium is greatly enhanced by anionic phospholipids,may cross-link plasma membrane phospholipids with actin and the cytoskeleton and be involved with exocytosis. Heat-stress response may also involve Annexin-2.