The best known family of Ca2+-regulated proteins is the “EF-hand” group, which includes parvalbumin, calmodulin, troponins, and other small, soluble proteins (Kretsinger, 1980). These proteins bind Ca2+ with high affinity and, in some cases, subsequently activate enzymes or contractile proteins. In recent years, a second group of Ca2+-binding proteins has come to be recognized. These are widely distributed, phospholipid-and membrane-binding proteins. They may be important in the control of cell proliferation through their modulation of arachidonic acid metabolism and because they are substrates of growth factorreceptor kinases. These proteins were first identified, and isolated, by their