Calcium ion is thought to play an important role in the intracellular signal transduction system and transfer its information through Ca(2+)-receptive proteins. Among many calcium receptive proteins, EF-hand type calcium receptive protein family are being investigated quite extensively. Calmodulin, one of representative EF-hand protein, localizes ubiquitously in many cells and tissues. This protein is involved in a general signal transduction system, such as, cell proliferation and differentiation. On the other hand, S-100 protein are distributed in specific cells and play specified roles.