基金Acknowledgments We thank Dr Lena Claesson-Welsh (Uppsala University), and PIs of Model Animal Research Center (MARC, Nanjing University) for the helpful discussion about the work, and Yanlan Cao, Wenting Shi and all the staff in the MARC Animal facility of Nanjing University for excellent technical assistance. This work wasfinancially supported by grants from the National Natural Science Foundation of China (30771069, 30671038, and 30930028), the Ministry of Science and Technology of China (2006CB943500), and the Ministry of Education of China (NCET: Program for New Century Excellent Talents in University).