Center for Computational Systems Biology, Fudan University, Shanghai, Peoples Republic of China. jzhang080@gmail.com|Center for Computational Systems Biology, Fudan University, Shanghai, Peoples Republic of China. jzhang080@gmail.com|Center for Computational Systems Biology, Fudan University, Shanghai, Peoples Republic of China. jzhang080@gmail.com|Center for Computational Systems Biology, Fudan University, Shanghai, Peoples Republic of China. jzhang080@gmail.com