Zhao, D
Pan, C
Sun, J
Gilbert, C
Drews-Elger, K
Azzam, D J
Picon-Ruiz, M
Kim, M
Ullmer, W
El-Ashry, D
Creighton, C J
Slingerland, J M
Article History
Received: 18 November 2013
Revised: 16 May 2014
Accepted: 22 May 2014
First Online: 25 August 2014
Competing interests
: The authors declare no conflict of interest.