1. Cancer Research Center, School of Medicine, Xiamen University, Xiamen, Fujian 361005, P.R. China
2. Department of Gastrointestinal Surgery, Zhongshan Hospital of Xiamen University, Xiamen, Fujian 361004, P.R. China
3. Department of Basic Medical Science, School of Medicine, Xiamen University, Xiamen, Fujian 361005, P.R. China