Bioinformatics Research Group, SRI International, 333 Ravenswood Ave, Menlo Park, 94025, USA.|John Innes Centre, Department of Metabolic Biology, and the Institute of Food Research, Food & Health Programme, Norwich Research Park, Norfolk, NR4 7UH, UK.|Bioinformatics Research Group, SRI International, 333 Ravenswood Ave, Menlo Park, 94025, USA.|Bioinformatics Research Group, SRI International, 333 Ravenswood Ave, Menlo Park, 94025, USA. pkarp@ai.sri.com.