The gene expression data of S. cerevisiae is downloaded from Gene Expression Omnibus (GEO) database with the accession number GSE3431 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE3431), updated on June 08, 2012. It is in the form of a 9335 36 matrix. Each value represents the expression level of a gene obtained at a certain time points. This expression experiment contains 3 metabolic cycles of S. cerevisiae and each cycle includes 12 time points. There are 4981 common proteins between 5093 proteins in the PPI network and the gene products from gene expression profiles.