1. Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Cardiovascular Research Group and PharmaHungary Companies, Department of Biochemistry, University of Szeged, Dom ter 9, H-6720, Szeged, Hungary, and Laboratory of Functional Genomics, Biological Research Center of the Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary