[1] Natl Inst Child Hlth & Dev, Cell Biol & Metab Branch, Bethesda, MD 20892 USA
[2] Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA
[3] Affymetrix, Santa Clara, CA 95051 USA
[4] Univ Washington, Dept Comp Sci, Seattle, WA 98195 USA
[5] NCI, Mol Biol Lab, Bethesda, MD 20892 USA