Algorithm 1 Dynamic Network Construction

Input: A static PPI (S_PPI) network represented as Graph G = (V, E, W), a time series of the gene expression profile of each gene in G, parameter k.

Output: The active networks of each time point.

Step1: Identify two categories of genes, the time-dependent genes and the time-independent genes. using Equations (1) and (2), according to their expression profiles.

Step2: Filter out the noise genes in the time-independent genes.

Step3: Identify the active genes of each time point from the remaining two categories of genes by judging whether or not their expression values are above the threshold (calculated by Equation (3)).

Step4: Map the active genes of each time point to the S_PPI network and extract the active networks of each time point.