1 Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California, USA
2 Stem Cell Program, University of California at San Diego, La Jolla, California, USA
3 Institute for Genomic Medicine, University of California at San Diego, La Jolla, California, USA
8 Molecular Engineering Laboratory, A*STAR, Singapore
9 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore