1. Department of Oncology, Tai'an Central Hospital, Tai'an, Shandong 271000, P.R. China
2. Department of Neurosurgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266100, P.R. China
3. Department of Neurosurgery, The Second Affiliated Hospital of Shandong First Medical University and Shandong Academy of Medical Sciences, Tai'an, Shandong 270000, P.R. China
4. Institute of Basic Medicine of Shangdong, First Medical University and Shandong Academy of Medical Sciences, Tai'an, Shandong 270000, P.R. China