Cao et al. BMC Cancer 2010, 10:68 http://www.biomedcentral.com/1471-2407/10/68 Acknowledgements This research work was supported by NSF 30772476 and 30873084 (to Q.L.), NSF 30700974 (to J. X. C) and Postdoctoral Foundation of China 20060400775 (to J. X. C). We thank Min Yan, Li-Hui Wang, Jie Xu, Yan Zhao, Jin-E Yao and other members in Liu Lab for technical assistance. Author details 1State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat- sen University, 650 Dongfeng Road, Guangzhou 510060, PR China. 2The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA. 3Department of Pathology, University of Cambridge, Hills Road, Cambridge BS2 0QQ, UK. 4Department of Hematology, Third Affiliated Hospital, Sun Yat- sen University, 600 Tianhe Road, Guangzhou 510630, PR China. 5College of Life Sciences, Zhejiang University, 388 Yuhangtang Road, Hangzhou 310058, PR China. 6Department of Emergency, First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan 2nd Road, Guangzhou 510060, PR China. Authors’ contributions JXC, YXZ and QL designed and performed the study and wrote the manuscript. YXC, ZJL, ZMD, JYL, YL and FMZ also performed the migration, flow cytometry, subtraction suppression hybridization and northern blotting experiments, as well as assisted in revising it critically for important intellectual content. 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