- Ca2+ -dependent interaction of S100A1 with the sarcoplasmic reticulum Ca2+ -ATPase2a and phospholamban in the human heart. Kiewitz, R., Acklin, C., Schäfer, B.W., Maco, B., Uhrík, B., Wuytack, F., Erne, P., Heizmann, C.W. Biochem. Biophys. Res. Commun. (2003)