1. Department of Developmental Biology, Howard Hughes Medical Institute, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, 265 Campus Drive, Stanford, CA 94305, USA.
2. Janelia Farm Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA.
3. Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA.
4. BIOTEC, Technische Universität Dresden Tatzberg 47-51, 01307 Dresden, Germany.