1. Department of Oncology, Hebei General Hospital, Shijiazhuang, Hebei 050051, P.R. China
2. Second Department of Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
3. Experimental Animal Center, The Forth Hospital of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China