1. S. Chu and I. Herskowitz, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143–0448, USA. J. DeRisi, Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305–5428, USA. M. Eisen, Departments of Biochemistry and Genetics, Stanford University School of Medicine, Stanford, CA 94305–5428, USA. J. Mulholland and D. Botstein, Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305–5428, USA. P....