1. Stem Cell Group, Bioprocessing Technology Institute; Agency for Science, Technology and Research; 20 Biopolis Way, Centros, Level 4 Singapore 138668 Republic of Singapore
2. Institute for Stem Cell Biology and Regenerative Medicine; Stanford University; 265 Campus Drive Palo Alto CA 94305 USA
3. Institute of Molecular and Cellular Biology; Agency for Science, Technology and Research; Singapore 138668 Republic of Singapore
4. Department of Biological Sciences; National University of Singapore; Singapore 117543 Republic of Singapore