Molecular and Computational Biology, Department of Biology Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA. hge@usc.edu|Molecular and Computational Biology, Department of Biology Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA. hge@usc.edu|Molecular and Computational Biology, Department of Biology Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA. hge@usc.edu