1. Center for Systems Biology, Soochow University, No1. Shizi Street, Suzhou, Jiangsu 215006, China
2. School of Computer Science and Technology, Soochow University, No1. Shizi Street, Suzhou, Jiangsu 215006, China
3. Department of Experimental Medical Science, Lund University, SE-221 84 Lund, Sweden and
4. Department of Genetics and Systems Biology Institute, Yale University School of Medicine, West Haven, CT 06516, USA